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help / color / mirror / Atom feedFrom: Jehan-Guillaume de Rorthais <[email protected]>
Subject: [PATCH 2/3] Allocate hash batches related BufFile in a dedicated context
Date: Mon, 27 Mar 2023 15:54:39 +0200
---
src/backend/executor/nodeHash.c | 43 ++++++++++++++++-------
src/backend/executor/nodeHashjoin.c | 22 ++++++++----
src/backend/utils/sort/sharedtuplestore.c | 8 +++++
src/include/executor/hashjoin.h | 30 ++++++++++------
src/include/executor/nodeHashjoin.h | 2 +-
5 files changed, 75 insertions(+), 30 deletions(-)
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 5fd1c5553b..e529f50a3e 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -484,7 +484,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
*
* The hashtable control block is just palloc'd from the executor's
* per-query memory context. Everything else should be kept inside the
- * subsidiary hashCxt or batchCxt.
+ * subsidiary hashCxt, batchCxt or spillCxt.
*/
hashtable = palloc_object(HashJoinTableData);
hashtable->nbuckets = nbuckets;
@@ -538,6 +538,10 @@ ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
"HashBatchContext",
ALLOCSET_DEFAULT_SIZES);
+ hashtable->spillCxt = AllocSetContextCreate(hashtable->hashCxt,
+ "HashSpillContext",
+ ALLOCSET_DEFAULT_SIZES);
+
/* Allocate data that will live for the life of the hashjoin */
oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
@@ -570,12 +574,19 @@ ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
if (nbatch > 1 && hashtable->parallel_state == NULL)
{
+ MemoryContext oldctx;
+
/*
* allocate and initialize the file arrays in hashCxt (not needed for
* parallel case which uses shared tuplestores instead of raw files)
*/
+ oldctx = MemoryContextSwitchTo(hashtable->spillCxt);
+
hashtable->innerBatchFile = palloc0_array(BufFile *, nbatch);
hashtable->outerBatchFile = palloc0_array(BufFile *, nbatch);
+
+ MemoryContextSwitchTo(oldctx);
+
/* The files will not be opened until needed... */
/* ... but make sure we have temp tablespaces established for them */
PrepareTempTablespaces();
@@ -913,7 +924,6 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
int oldnbatch = hashtable->nbatch;
int curbatch = hashtable->curbatch;
int nbatch;
- MemoryContext oldcxt;
long ninmemory;
long nfreed;
HashMemoryChunk oldchunks;
@@ -934,13 +944,16 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
hashtable, nbatch, hashtable->spaceUsed);
#endif
- oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
-
if (hashtable->innerBatchFile == NULL)
{
+ MemoryContext oldcxt = MemoryContextSwitchTo(hashtable->spillCxt);
+
/* we had no file arrays before */
hashtable->innerBatchFile = palloc0_array(BufFile *, nbatch);
hashtable->outerBatchFile = palloc0_array(BufFile *, nbatch);
+
+ MemoryContextSwitchTo(oldcxt);
+
/* time to establish the temp tablespaces, too */
PrepareTempTablespaces();
}
@@ -951,8 +964,6 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
hashtable->outerBatchFile = repalloc0_array(hashtable->outerBatchFile, BufFile *, oldnbatch, nbatch);
}
- MemoryContextSwitchTo(oldcxt);
-
hashtable->nbatch = nbatch;
/*
@@ -1024,7 +1035,8 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
Assert(batchno > curbatch);
ExecHashJoinSaveTuple(HJTUPLE_MINTUPLE(hashTuple),
hashTuple->hashvalue,
- &hashtable->innerBatchFile[batchno]);
+ &hashtable->innerBatchFile[batchno],
+ hashtable->spillCxt);
hashtable->spaceUsed -= hashTupleSize;
nfreed++;
@@ -1683,7 +1695,8 @@ ExecHashTableInsert(HashJoinTable hashtable,
Assert(batchno > hashtable->curbatch);
ExecHashJoinSaveTuple(tuple,
hashvalue,
- &hashtable->innerBatchFile[batchno]);
+ &hashtable->innerBatchFile[batchno],
+ hashtable->spillCxt);
}
if (shouldFree)
@@ -2664,7 +2677,8 @@ ExecHashRemoveNextSkewBucket(HashJoinTable hashtable)
/* Put the tuple into a temp file for later batches */
Assert(batchno > hashtable->curbatch);
ExecHashJoinSaveTuple(tuple, hashvalue,
- &hashtable->innerBatchFile[batchno]);
+ &hashtable->innerBatchFile[batchno],
+ hashtable->spillCxt);
pfree(hashTuple);
hashtable->spaceUsed -= tupleSize;
hashtable->spaceUsedSkew -= tupleSize;
@@ -3093,8 +3107,11 @@ ExecParallelHashJoinSetUpBatches(HashJoinTable hashtable, int nbatch)
pstate->nbatch = nbatch;
batches = dsa_get_address(hashtable->area, pstate->batches);
- /* Use hash join memory context. */
- oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
+ /*
+ * Use hash join spill memory context to allocate accessors and their
+ * buffers
+ */
+ oldcxt = MemoryContextSwitchTo(hashtable->spillCxt);
/* Allocate this backend's accessor array. */
hashtable->nbatch = nbatch;
@@ -3196,8 +3213,8 @@ ExecParallelHashEnsureBatchAccessors(HashJoinTable hashtable)
*/
Assert(DsaPointerIsValid(pstate->batches));
- /* Use hash join memory context. */
- oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
+ /* Use hash join spill memory context to allocate accessors */
+ oldcxt = MemoryContextSwitchTo(hashtable->spillCxt);
/* Allocate this backend's accessor array. */
hashtable->nbatch = pstate->nbatch;
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index a39164c15d..8618e0df40 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -491,7 +491,8 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
Assert(parallel_state == NULL);
Assert(batchno > hashtable->curbatch);
ExecHashJoinSaveTuple(mintuple, hashvalue,
- &hashtable->outerBatchFile[batchno]);
+ &hashtable->outerBatchFile[batchno],
+ hashtable->spillCxt);
if (shouldFree)
heap_free_minimal_tuple(mintuple);
@@ -1313,21 +1314,30 @@ ExecParallelHashJoinNewBatch(HashJoinState *hjstate)
* The data recorded in the file for each tuple is its hash value,
* then the tuple in MinimalTuple format.
*
- * Note: it is important always to call this in the regular executor
- * context, not in a shorter-lived context; else the temp file buffers
- * will get messed up.
+ * If this is the first write to the batch file, this function first
+ * create it. The associated BufFile buffer is allocated in the given
+ * context. It is important to always give the HashSpillContext
+ * context. First to avoid a shorter-lived context, else the temp file
+ * buffers will get messed up. Second, for a better accounting of the
+ * spilling memory consumption.
+ *
*/
void
ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
- BufFile **fileptr)
+ BufFile **fileptr, MemoryContext cxt)
{
BufFile *file = *fileptr;
if (file == NULL)
{
- /* First write to this batch file, so open it. */
+ MemoryContext oldctx;
+
+ oldctx = MemoryContextSwitchTo(cxt);
+
file = BufFileCreateTemp(false);
*fileptr = file;
+
+ MemoryContextSwitchTo(oldctx);
}
BufFileWrite(file, &hashvalue, sizeof(uint32));
diff --git a/src/backend/utils/sort/sharedtuplestore.c b/src/backend/utils/sort/sharedtuplestore.c
index 0831249159..236be65f22 100644
--- a/src/backend/utils/sort/sharedtuplestore.c
+++ b/src/backend/utils/sort/sharedtuplestore.c
@@ -308,11 +308,15 @@ sts_puttuple(SharedTuplestoreAccessor *accessor, void *meta_data,
{
SharedTuplestoreParticipant *participant;
char name[MAXPGPATH];
+ MemoryContext oldcxt;
/* Create one. Only this backend will write into it. */
sts_filename(name, accessor, accessor->participant);
+
+ oldcxt = MemoryContextSwitchTo(accessor->context);
accessor->write_file =
BufFileCreateFileSet(&accessor->fileset->fs, name);
+ MemoryContextSwitchTo(oldcxt);
/* Set up the shared state for this backend's file. */
participant = &accessor->sts->participants[accessor->participant];
@@ -527,11 +531,15 @@ sts_parallel_scan_next(SharedTuplestoreAccessor *accessor, void *meta_data)
if (accessor->read_file == NULL)
{
char name[MAXPGPATH];
+ MemoryContext oldcxt;
sts_filename(name, accessor, accessor->read_participant);
+
+ oldcxt = MemoryContextSwitchTo(accessor->context);
accessor->read_file =
BufFileOpenFileSet(&accessor->fileset->fs, name, O_RDONLY,
false);
+ MemoryContextSwitchTo(oldcxt);
}
/* Seek and load the chunk header. */
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index 8ee59d2c71..09113f0192 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -23,22 +23,31 @@
/* ----------------------------------------------------------------
* hash-join hash table structures
*
- * Each active hashjoin has a HashJoinTable control block, which is
- * palloc'd in the executor's per-query context. All other storage needed
- * for the hashjoin is kept in private memory contexts, two for each hashjoin.
- * This makes it easy and fast to release the storage when we don't need it
- * anymore. (Exception: data associated with the temp files lives in the
- * per-query context too, since we always call buffile.c in that context.)
+ * Each active hashjoin has a HashJoinTable structure, which is
+ * palloc'd in the executor's per-query context. Other storages needed for
+ * each hashjoin is kept in child contexts, three for each hashjoin:
+ * - HashTableContext (hashCxt): the parent hash table storage context
+ * - HashSpillContext (spillCxt): storage for temp files buffers
+ * - HashBatchContext (batchCxt): storage for a batch in serial hash join
*
* The hashtable contexts are made children of the per-query context, ensuring
* that they will be discarded at end of statement even if the join is
* aborted early by an error. (Likewise, any temporary files we make will
* be cleaned up by the virtual file manager in event of an error.)
*
- * Storage that should live through the entire join is allocated from the
- * "hashCxt", while storage that is only wanted for the current batch is
- * allocated in the "batchCxt". By resetting the batchCxt at the end of
- * each batch, we free all the per-batch storage reliably and without tedium.
+ * The "hashCxt" context makes it easy and fast to release the storage when we
+ * don't need it anymore. Storage that should live through the entire join is
+ * allocated from the "hashCxt" (mainly hash's meta datas).
+ *
+ * Data associated with temp files lives in the "spillCxt" context which lives
+ * during the entire join as temp files might need to survives batches. These
+ * files are explicitly destroyed by calling BufFileClose() when the code is
+ * done with them. The aim of this context is to help accounting the memory
+ * allocations dedicated to temp files and their buffers.
+ *
+ * Finaly, storage that is only wanted for the current batch is allocated in
+ * the "batchCxt". By resetting the batchCxt at the end of each batch, we free
+ * all the per-batch storage reliably and without tedium.
*
* During first scan of inner relation, we get its tuples from executor.
* If nbatch > 1 then tuples that don't belong in first batch get saved
@@ -350,6 +359,7 @@ typedef struct HashJoinTableData
MemoryContext hashCxt; /* context for whole-hash-join storage */
MemoryContext batchCxt; /* context for this-batch-only storage */
+ MemoryContext spillCxt; /* context for spilling to temp files */
/* used for dense allocation of tuples (into linked chunks) */
HashMemoryChunk chunks; /* one list for the whole batch */
diff --git a/src/include/executor/nodeHashjoin.h b/src/include/executor/nodeHashjoin.h
index d367070883..958df42240 100644
--- a/src/include/executor/nodeHashjoin.h
+++ b/src/include/executor/nodeHashjoin.h
@@ -29,6 +29,6 @@ extern void ExecHashJoinInitializeWorker(HashJoinState *state,
ParallelWorkerContext *pwcxt);
extern void ExecHashJoinSaveTuple(MinimalTuple tuple, uint32 hashvalue,
- BufFile **fileptr);
+ BufFile **fileptr, MemoryContext spillcxt);
#endif /* NODEHASHJOIN_H */
--
2.40.1
--MP_/WHuN2qnG.U=I.v0AxCf+Cxe--
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Subject: Re: [PATCH 2/3] Allocate hash batches related BufFile in a dedicated context
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