From 8526bcb2df76d5171b4f4d6dc7a97560a73a5eff Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Tue, 19 Dec 2017 12:21:56 -0500 Subject: Try again to fix accumulation of parallel worker instrumentation. When a Gather or Gather Merge node is started and stopped multiple times, accumulate instrumentation data only once, at the end, instead of after each execution, to avoid recording inflated totals. Commit 778e78ae9fa51e58f41cbdc72b293291d02d8984, the previous attempt at a fix, instead reset the state after every execution, which worked for the general instrumentation data but had problems for the additional instrumentation specific to Sort and Hash nodes. Report by hubert depesz lubaczewski. Analysis and fix by Amit Kapila, following a design proposal from Thomas Munro, with a comment tweak by me. Discussion: http://postgr.es/m/20171127175631.GA405@depesz.com --- src/backend/executor/execParallel.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) (limited to 'src/backend/executor/execParallel.c') diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c index 6b6064637b8..02b5aa517b5 100644 --- a/src/backend/executor/execParallel.c +++ b/src/backend/executor/execParallel.c @@ -899,12 +899,8 @@ ExecParallelReInitializeDSM(PlanState *planstate, pcxt); break; case T_HashState: - /* even when not parallel-aware, for EXPLAIN ANALYZE */ - ExecHashReInitializeDSM((HashState *) planstate, pcxt); - break; case T_SortState: - /* even when not parallel-aware, for EXPLAIN ANALYZE */ - ExecSortReInitializeDSM((SortState *) planstate, pcxt); + /* these nodes have DSM state, but no reinitialization is required */ break; default: @@ -977,7 +973,7 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate, /* * Finish parallel execution. We wait for parallel workers to finish, and - * accumulate their buffer usage and instrumentation. + * accumulate their buffer usage. */ void ExecParallelFinish(ParallelExecutorInfo *pei) @@ -1023,23 +1019,23 @@ ExecParallelFinish(ParallelExecutorInfo *pei) for (i = 0; i < nworkers; i++) InstrAccumParallelQuery(&pei->buffer_usage[i]); - /* Finally, accumulate instrumentation, if any. */ - if (pei->instrumentation) - ExecParallelRetrieveInstrumentation(pei->planstate, - pei->instrumentation); - pei->finished = true; } /* - * Clean up whatever ParallelExecutorInfo resources still exist after - * ExecParallelFinish. We separate these routines because someone might - * want to examine the contents of the DSM after ExecParallelFinish and - * before calling this routine. + * Accumulate instrumentation, and then clean up whatever ParallelExecutorInfo + * resources still exist after ExecParallelFinish. We separate these + * routines because someone might want to examine the contents of the DSM + * after ExecParallelFinish and before calling this routine. */ void ExecParallelCleanup(ParallelExecutorInfo *pei) { + /* Accumulate instrumentation, if any. */ + if (pei->instrumentation) + ExecParallelRetrieveInstrumentation(pei->planstate, + pei->instrumentation); + /* Free any serialized parameters. */ if (DsaPointerIsValid(pei->param_exec)) { -- cgit v1.2.3