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Revert "Fix race in Parallel Hash Join batch cleanup."

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This reverts commit 8fa2478b40.

Discussion: https://postgr.es/m/CA%2BhUKGJmcqAE3MZeDCLLXa62cWM0AJbKmp2JrJYaJ86bz36LFA%40mail.gmail.com
This commit is contained in:
Thomas Munro
2021-03-18 01:06:01 +13:00
parent 8fa2478b40
commit b9ed85698f
3 changed files with 32 additions and 58 deletions
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47
src/backend/executor/nodeHash.c
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@ -333,21 +333,14 @@ MultiExecParallelHash(HashState *node)
hashtable->nbuckets = pstate->nbuckets;
hashtable->log2_nbuckets = my_log2(hashtable->nbuckets);
hashtable->totalTuples = pstate->total_tuples;
/*
* Unless we're completely done and the batch state has been freed, make
* sure we have accessors.
*/
if (BarrierPhase(build_barrier) < PHJ_BUILD_DONE)
ExecParallelHashEnsureBatchAccessors(hashtable);
ExecParallelHashEnsureBatchAccessors(hashtable);
/*
* The next synchronization point is in ExecHashJoin's HJ_BUILD_HASHTABLE
* case, which will bring the build phase to PHJ_BUILD_RUNNING (if it isn't
* case, which will bring the build phase to PHJ_BUILD_DONE (if it isn't
* there already).
*/
Assert(BarrierPhase(build_barrier) == PHJ_BUILD_HASHING_OUTER ||
BarrierPhase(build_barrier) == PHJ_BUILD_RUNNING ||
BarrierPhase(build_barrier) == PHJ_BUILD_DONE);
}
@ -631,7 +624,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
/*
* The next Parallel Hash synchronization point is in
* MultiExecParallelHash(), which will progress it all the way to
* PHJ_BUILD_RUNNING. The caller must not return control from this
* PHJ_BUILD_DONE. The caller must not return control from this
* executor node between now and then.
*/
}
@ -3026,11 +3019,14 @@ ExecParallelHashEnsureBatchAccessors(HashJoinTable hashtable)
}
/*
* We should never see a state where the batch-tracking array is freed,
* because we should have given up sooner if we join when the build barrier
* has reached the PHJ_BUILD_DONE phase.
* It's possible for a backend to start up very late so that the whole
* join is finished and the shm state for tracking batches has already
* been freed by ExecHashTableDetach(). In that case we'll just leave
* hashtable->batches as NULL so that ExecParallelHashJoinNewBatch() gives
* up early.
*/
Assert(DsaPointerIsValid(pstate->batches));
if (!DsaPointerIsValid(pstate->batches))
return;
/* Use hash join memory context. */
oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
@ -3150,17 +3146,9 @@ ExecHashTableDetachBatch(HashJoinTable hashtable)
void
ExecHashTableDetach(HashJoinTable hashtable)
{
ParallelHashJoinState *pstate = hashtable->parallel_state;
/*
* If we're involved in a parallel query, we must either have got all the
* way to PHJ_BUILD_RUNNING, or joined too late and be in PHJ_BUILD_DONE.
*/
Assert(!pstate ||
BarrierPhase(&pstate->build_barrier) >= PHJ_BUILD_RUNNING);
if (pstate && BarrierPhase(&pstate->build_barrier) == PHJ_BUILD_RUNNING)
if (hashtable->parallel_state)
{
ParallelHashJoinState *pstate = hashtable->parallel_state;
int i;
/* Make sure any temporary files are closed. */
@ -3176,22 +3164,17 @@ ExecHashTableDetach(HashJoinTable hashtable)
}
/* If we're last to detach, clean up shared memory. */
if (BarrierArriveAndDetach(&pstate->build_barrier))
if (BarrierDetach(&pstate->build_barrier))
{
/*
* Late joining processes will see this state and give up
* immediately.
*/
Assert(BarrierPhase(&pstate->build_barrier) == PHJ_BUILD_DONE);
if (DsaPointerIsValid(pstate->batches))
{
dsa_free(hashtable->area, pstate->batches);
pstate->batches = InvalidDsaPointer;
}
}
hashtable->parallel_state = NULL;
}
hashtable->parallel_state = NULL;
}
/*