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[PATCH v3 3/7] Row pattern recognition patch (planner). 224+ messages / 2 participants [nested] [flat]
* [PATCH v3 3/7] Row pattern recognition patch (planner). @ 2023-07-26 10:49 Tatsuo Ishii <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Tatsuo Ishii @ 2023-07-26 10:49 UTC (permalink / raw) --- src/backend/optimizer/plan/createplan.c | 19 ++++++++++++++----- src/include/nodes/plannodes.h | 12 ++++++++++++ 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index af48109058..4b1ae0fb21 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -286,9 +286,9 @@ static WindowAgg *make_windowagg(List *tlist, Index winref, int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations, int frameOptions, Node *startOffset, Node *endOffset, Oid startInRangeFunc, Oid endInRangeFunc, - Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, - List *runCondition, List *qual, bool topWindow, - Plan *lefttree); + Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, List *runCondition, + RPSkipTo rpSkipTo, List *patternVariable, List *patternRegexp, List *defineClause, + List *qual, bool topWindow, Plan *lefttree); static Group *make_group(List *tlist, List *qual, int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations, Plan *lefttree); @@ -2679,6 +2679,10 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path) wc->inRangeAsc, wc->inRangeNullsFirst, wc->runCondition, + wc->rpSkipTo, + wc->patternVariable, + wc->patternRegexp, + wc->defineClause, best_path->qual, best_path->topwindow, subplan); @@ -6582,8 +6586,9 @@ make_windowagg(List *tlist, Index winref, int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations, int frameOptions, Node *startOffset, Node *endOffset, Oid startInRangeFunc, Oid endInRangeFunc, - Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, - List *runCondition, List *qual, bool topWindow, Plan *lefttree) + Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, List *runCondition, + RPSkipTo rpSkipTo, List *patternVariable, List *patternRegexp, List *defineClause, + List *qual, bool topWindow, Plan *lefttree) { WindowAgg *node = makeNode(WindowAgg); Plan *plan = &node->plan; @@ -6609,6 +6614,10 @@ make_windowagg(List *tlist, Index winref, node->inRangeAsc = inRangeAsc; node->inRangeNullsFirst = inRangeNullsFirst; node->topWindow = topWindow; + node->rpSkipTo = rpSkipTo, + node->patternVariable = patternVariable; + node->patternRegexp = patternRegexp; + node->defineClause = defineClause; plan->targetlist = tlist; plan->lefttree = lefttree; diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h index 1b787fe031..cc942b9c12 100644 --- a/src/include/nodes/plannodes.h +++ b/src/include/nodes/plannodes.h @@ -1096,6 +1096,18 @@ typedef struct WindowAgg /* nulls sort first for in_range tests? */ bool inRangeNullsFirst; + /* Row Pattern Recognition AFTER MACH SKIP clause */ + RPSkipTo rpSkipTo; /* Row Pattern Skip To type */ + + /* Row Pattern Recognition PATTERN variable name (list of String) */ + List *patternVariable; + + /* Row Pattern Recognition PATTERN regular expression quantifier ('+' or ''. list of String) */ + List *patternRegexp; + + /* Row Pattern Recognition DEFINE clause (list of TargetEntry) */ + List *defineClause; + /* * false for all apart from the WindowAgg that's closest to the root of * the plan -- 2.25.1 ----Next_Part(Wed_Jul_26_21_21_34_2023_317)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v3-0004-Row-pattern-recognition-patch-executor.patch" ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
* [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 224+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Xf36GNcW+0xZNily Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 224+ messages in thread
end of thread, other threads:[~2026-07-09 19:20 UTC | newest] Thread overview: 224+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-07-26 10:49 [PATCH v3 3/7] Row pattern recognition patch (planner). Tatsuo Ishii <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v2 1/9] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
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