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[PATCH 03/10] Make sure published XIDs are persistent 2+ messages / 2 participants [nested] [flat]
* [PATCH 03/10] Make sure published XIDs are persistent @ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw) pg_xact_status() premises that XIDs obtained by pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But XIDs are not guaranteed to go beyond WAL buffers before commit and thus XIDs may vanish if server crashes before commit. This patch guarantees the XID shown by the functions to be flushed out to disk. Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com --- src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------ src/backend/access/transam/xlog.c | 2 +- src/backend/utils/adt/xid8funcs.c | 12 ++++++- src/include/access/xact.h | 3 +- 4 files changed, 59 insertions(+), 13 deletions(-) diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 6395a9b240..38e978d238 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -201,7 +201,7 @@ typedef struct TransactionStateData int prevSecContext; /* previous SecurityRestrictionContext */ bool prevXactReadOnly; /* entry-time xact r/o state */ bool startedInRecovery; /* did we start in recovery? */ - bool didLogXid; /* has xid been included in WAL record? */ + XLogRecPtr minLSN; /* LSN needed to reach to record the xid */ int parallelModeLevel; /* Enter/ExitParallelMode counter */ bool chain; /* start a new block after this one */ bool assigned; /* assigned to top-level XID */ @@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void) * MarkCurrentTransactionIdLoggedIfAny * * Remember that the current xid - if it is assigned - now has been wal logged. + * + * upto is the LSN up to which we need to flush WAL to ensure the current xid + * to be persistent. See EnsureCurrentTransactionIdLogged(). */ void -MarkCurrentTransactionIdLoggedIfAny(void) +MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto) { - if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId)) - CurrentTransactionState->didLogXid = true; + if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) && + XLogRecPtrIsInvalid(CurrentTransactionState->minLSN)) + CurrentTransactionState->minLSN = upto; } +/* + * EnsureCurrentTransactionIdLogged + * + * Make sure that the current top XID is WAL-logged. + */ +void +EnsureTopTransactionIdLogged(void) +{ + /* + * We need at least one WAL record for the current top transaction to be + * flushed out. Write one if we don't have one yet. + */ + if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) + { + xl_xact_assignment xlrec; + + xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId); + Assert(TransactionIdIsValid(xlrec.xtop)); + xlrec.nsubxacts = 0; + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment); + TopTransactionStateData.minLSN = + XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); + } + + XLogFlush(TopTransactionStateData.minLSN); +} /* * GetStableLatestTransactionId @@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s) * When wal_level=logical, guarantee that a subtransaction's xid can only * be seen in the WAL stream if its toplevel xid has been logged before. * If necessary we log an xact_assignment record with fewer than - * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set + * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set * for a transaction even though it appears in a WAL record, we just might * superfluously log something. That can happen when an xid is included * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in * xl_standby_locks. */ if (isSubXact && XLogLogicalInfoActive() && - !TopTransactionStateData.didLogXid) + XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) log_unknown_top = true; /* @@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s) log_unknown_top) { xl_xact_assignment xlrec; + XLogRecPtr endptr; /* * xtop is always set by now because we recurse up transaction @@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s) XLogRegisterData((char *) unreportedXids, nUnreportedXids * sizeof(TransactionId)); - (void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); + endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); nUnreportedXids = 0; - /* mark top, not current xact as having been logged */ - TopTransactionStateData.didLogXid = true; + + /* set minLSN of top, not of current xact if not yet */ + if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) + TopTransactionStateData.minLSN = endptr; } } } @@ -2022,7 +2057,7 @@ StartTransaction(void) * initialize reported xid accounting */ nUnreportedXids = 0; - s->didLogXid = false; + s->minLSN = InvalidXLogRecPtr; /* * must initialize resource-management stuff first diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 15da91a8dd..6eb46ea8a7 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata, */ WALInsertLockRelease(); - MarkCurrentTransactionIdLoggedIfAny(); + MarkCurrentTransactionIdLoggedIfAny(EndPos); END_CRIT_SECTION(); diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c index cc2b4ac797..992482f8c8 100644 --- a/src/backend/utils/adt/xid8funcs.c +++ b/src/backend/utils/adt/xid8funcs.c @@ -357,6 +357,8 @@ bad_format: Datum pg_current_xact_id(PG_FUNCTION_ARGS) { + FullTransactionId xid; + /* * Must prevent during recovery because if an xid is not assigned we try * to assign one, which would fail. Programs already rely on this function @@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS) */ PreventCommandDuringRecovery("pg_current_xact_id()"); - PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId()); + xid = GetTopFullTransactionId(); + + /* the XID is going to be published, make sure it is psersistent */ + EnsureTopTransactionIdLogged(); + + PG_RETURN_FULLTRANSACTIONID(xid); } /* @@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS) if (!FullTransactionIdIsValid(topfxid)) PG_RETURN_NULL(); + /* the XID is going to be published, make sure it is psersistent */ + EnsureTopTransactionIdLogged(); + PG_RETURN_FULLTRANSACTIONID(topfxid); } diff --git a/src/include/access/xact.h b/src/include/access/xact.h index 34cfaf542c..a61e4d6da5 100644 --- a/src/include/access/xact.h +++ b/src/include/access/xact.h @@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void); extern FullTransactionId GetTopFullTransactionIdIfAny(void); extern FullTransactionId GetCurrentFullTransactionId(void); extern FullTransactionId GetCurrentFullTransactionIdIfAny(void); -extern void MarkCurrentTransactionIdLoggedIfAny(void); +extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto); +extern void EnsureTopTransactionIdLogged(void); extern bool SubTransactionIsActive(SubTransactionId subxid); extern CommandId GetCurrentCommandId(bool used); extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts); -- 2.17.0 --jozmn01XJZjDjM3N Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0004-wal_compression_method-default-to-zlib.patch" ^ permalink raw reply [nested|flat] 2+ messages in thread
* 001_rep_changes.pl fails due to publisher stuck on shutdown @ 2024-05-29 11:00 Alexander Lakhin <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Alexander Lakhin @ 2024-05-29 11:00 UTC (permalink / raw) To: pgsql-hackers Hello hackers, As a recent buildfarm test failure [1] shows: [14:33:02.374](0.333s) ok 23 - update works with dropped subscriber column ### Stopping node "publisher" using mode fast # Running: pg_ctl -D /home/bf/bf-build/adder/HEAD/pgsql.build/testrun/subscription/001_rep_changes/data/t_001_rep_changes_publisher_data/pgdata -m fast stop waiting for server to shut down.. ... ... ... .. failed pg_ctl: server does not shut down # pg_ctl stop failed: 256 # Postmaster PID for node "publisher" is 2222549 [14:39:04.375](362.001s) Bail out! pg_ctl stop failed 001_rep_changes_publisher.log 2024-05-16 14:33:02.907 UTC [2238704][client backend][4/22:0] LOG: statement: DELETE FROM tab_rep 2024-05-16 14:33:02.925 UTC [2238704][client backend][:0] LOG: disconnection: session time: 0:00:00.078 user=bf database=postgres host=[local] 2024-05-16 14:33:02.939 UTC [2222549][postmaster][:0] LOG: received fast shutdown request 2024-05-16 14:33:03.000 UTC [2222549][postmaster][:0] LOG: aborting any active transactions 2024-05-16 14:33:03.049 UTC [2222549][postmaster][:0] LOG: background worker "logical replication launcher" (PID 2223110) exited with exit code 1 2024-05-16 14:33:03.062 UTC [2222901][checkpointer][:0] LOG: shutting down 2024-05-16 14:39:04.377 UTC [2222549][postmaster][:0] LOG: received immediate shutdown request 2024-05-16 14:39:04.382 UTC [2222549][postmaster][:0] LOG: database system is shut down the publisher node may hang on stopping. I reproduced the failure (with aggressive autovacuum) locally and discovered that it happens because: 1) checkpointer calls WalSndInitStopping() (which sends PROCSIG_WALSND_INIT_STOPPING to walsender), and then spins inside WalSndWaitStopping() indefinitely, because: 2) walsender receives the signal, sets got_STOPPING = true, but can't exit WalSndLoop(): 3) it never sets got_SIGUSR2 (to get into WalSndDone()) in XLogSendLogical(): 4) it never sets WalSndCaughtUp to true: 5) logical_decoding_ctx->reader->EndRecPtr can't reach flushPtr in XLogSendLogical(): 6) EndRecPtr doesn't advance in XLogNextRecord(): 7) XLogDecodeNextRecord() fails do decode a record that crosses a page boundary: 8) ReadPageInternal() (commented "Wait for the next page to become available") constantly returns XLREAD_FAIL: 9) state->routine.page_read()/logical_read_xlog_page() constantly returns -1: 10) flushptr = WalSndWaitForWal() stops advancing, because got_STOPPING == true (see 2). That is, walsender doesn't let itself to catch up, if it gets the stop signal when it's lagging behind and decoding a record requires reading the next wal page. Please look at the reproducing test (based on 001_rep_changes.pl) attached. If fails for me as below: # 17 Bailout called. Further testing stopped: pg_ctl stop failed FAILED--Further testing stopped: pg_ctl stop failed make: *** [Makefile:21: check] Ошибка 255 [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=adder&dt=2024-05-16%2014%3A22%3A38 [2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dikkop&dt=2024-04-24%2014%3A38%3A35 (apparently the same) Best regards, Alexander Attachments: [application/x-perl] 099_walsender_stop.pl (1.7K, ../../[email protected]/2-099_walsender_stop.pl) download ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2024-05-29 11:00 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-03-08 06:43 [PATCH 03/10] Make sure published XIDs are persistent Kyotaro Horiguchi <[email protected]> 2024-05-29 11:00 001_rep_changes.pl fails due to publisher stuck on shutdown Alexander Lakhin <[email protected]>
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