Improve division of labor between execParallel.c and nodeGather[Merge].c.
Move the responsibility for creating/destroying TupleQueueReaders into execParallel.c, to avoid duplicative coding in nodeGather.c and nodeGatherMerge.c. Also, instead of having DestroyTupleQueueReader do shm_mq_detach, do it in the caller (which is now only ExecParallelFinish). This means execParallel.c does both the attaching and detaching of the tuple-queue-reader shm_mqs, which seems less weird than the previous arrangement. These changes also eliminate a vestigial memory leak (of the pei->tqueue array). It's now demonstrable that rescans of Gather or GatherMerge don't leak memory. Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us
This commit is contained in:
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c039ba0716
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51daa7bdb3
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@ -534,9 +534,12 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers,
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shm_toc_insert(pcxt->toc, PARALLEL_KEY_BUFFER_USAGE, bufusage_space);
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shm_toc_insert(pcxt->toc, PARALLEL_KEY_BUFFER_USAGE, bufusage_space);
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pei->buffer_usage = bufusage_space;
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pei->buffer_usage = bufusage_space;
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/* Set up tuple queues. */
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/* Set up the tuple queues that the workers will write into. */
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pei->tqueue = ExecParallelSetupTupleQueues(pcxt, false);
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pei->tqueue = ExecParallelSetupTupleQueues(pcxt, false);
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/* We don't need the TupleQueueReaders yet, though. */
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pei->reader = NULL;
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/*
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/*
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* If instrumentation options were supplied, allocate space for the data.
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* If instrumentation options were supplied, allocate space for the data.
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* It only gets partially initialized here; the rest happens during
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* It only gets partially initialized here; the rest happens during
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@ -603,6 +606,37 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers,
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return pei;
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return pei;
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}
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}
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/*
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* Set up tuple queue readers to read the results of a parallel subplan.
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* All the workers are expected to return tuples matching tupDesc.
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*
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* This is separate from ExecInitParallelPlan() because we can launch the
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* worker processes and let them start doing something before we do this.
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*/
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void
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ExecParallelCreateReaders(ParallelExecutorInfo *pei,
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TupleDesc tupDesc)
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{
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int nworkers = pei->pcxt->nworkers_launched;
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int i;
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Assert(pei->reader == NULL);
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if (nworkers > 0)
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{
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pei->reader = (TupleQueueReader **)
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palloc(nworkers * sizeof(TupleQueueReader *));
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for (i = 0; i < nworkers; i++)
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{
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shm_mq_set_handle(pei->tqueue[i],
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pei->pcxt->worker[i].bgwhandle);
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pei->reader[i] = CreateTupleQueueReader(pei->tqueue[i],
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tupDesc);
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}
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}
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}
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/*
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/*
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* Re-initialize the parallel executor shared memory state before launching
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* Re-initialize the parallel executor shared memory state before launching
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* a fresh batch of workers.
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* a fresh batch of workers.
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@ -616,6 +650,7 @@ ExecParallelReinitialize(PlanState *planstate,
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ReinitializeParallelDSM(pei->pcxt);
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ReinitializeParallelDSM(pei->pcxt);
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pei->tqueue = ExecParallelSetupTupleQueues(pei->pcxt, true);
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pei->tqueue = ExecParallelSetupTupleQueues(pei->pcxt, true);
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pei->reader = NULL;
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pei->finished = false;
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pei->finished = false;
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/* Traverse plan tree and let each child node reset associated state. */
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/* Traverse plan tree and let each child node reset associated state. */
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@ -741,16 +776,45 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
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void
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void
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ExecParallelFinish(ParallelExecutorInfo *pei)
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ExecParallelFinish(ParallelExecutorInfo *pei)
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{
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{
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int nworkers = pei->pcxt->nworkers_launched;
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int i;
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int i;
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/* Make this be a no-op if called twice in a row. */
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if (pei->finished)
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if (pei->finished)
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return;
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return;
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/* First, wait for the workers to finish. */
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/*
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* Detach from tuple queues ASAP, so that any still-active workers will
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* notice that no further results are wanted.
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*/
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if (pei->tqueue != NULL)
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{
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for (i = 0; i < nworkers; i++)
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shm_mq_detach(pei->tqueue[i]);
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pfree(pei->tqueue);
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pei->tqueue = NULL;
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}
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/*
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* While we're waiting for the workers to finish, let's get rid of the
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* tuple queue readers. (Any other local cleanup could be done here too.)
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*/
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if (pei->reader != NULL)
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{
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for (i = 0; i < nworkers; i++)
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DestroyTupleQueueReader(pei->reader[i]);
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pfree(pei->reader);
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pei->reader = NULL;
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}
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/* Now wait for the workers to finish. */
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WaitForParallelWorkersToFinish(pei->pcxt);
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WaitForParallelWorkersToFinish(pei->pcxt);
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/* Next, accumulate buffer usage. */
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/*
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for (i = 0; i < pei->pcxt->nworkers_launched; ++i)
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* Next, accumulate buffer usage. (This must wait for the workers to
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* finish, or we might get incomplete data.)
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*/
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for (i = 0; i < nworkers; i++)
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InstrAccumParallelQuery(&pei->buffer_usage[i]);
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InstrAccumParallelQuery(&pei->buffer_usage[i]);
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/* Finally, accumulate instrumentation, if any. */
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/* Finally, accumulate instrumentation, if any. */
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@ -130,7 +130,6 @@ ExecGather(PlanState *pstate)
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{
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{
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GatherState *node = castNode(GatherState, pstate);
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GatherState *node = castNode(GatherState, pstate);
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TupleTableSlot *fslot = node->funnel_slot;
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TupleTableSlot *fslot = node->funnel_slot;
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int i;
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TupleTableSlot *slot;
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TupleTableSlot *slot;
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ExprContext *econtext;
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ExprContext *econtext;
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@ -173,33 +172,30 @@ ExecGather(PlanState *pstate)
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LaunchParallelWorkers(pcxt);
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LaunchParallelWorkers(pcxt);
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/* We save # workers launched for the benefit of EXPLAIN */
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/* We save # workers launched for the benefit of EXPLAIN */
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node->nworkers_launched = pcxt->nworkers_launched;
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node->nworkers_launched = pcxt->nworkers_launched;
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node->nreaders = 0;
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node->nextreader = 0;
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/* Set up tuple queue readers to read the results. */
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/* Set up tuple queue readers to read the results. */
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if (pcxt->nworkers_launched > 0)
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if (pcxt->nworkers_launched > 0)
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{
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{
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node->reader = palloc(pcxt->nworkers_launched *
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ExecParallelCreateReaders(node->pei,
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sizeof(TupleQueueReader *));
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fslot->tts_tupleDescriptor);
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/* Make a working array showing the active readers */
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for (i = 0; i < pcxt->nworkers_launched; ++i)
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node->nreaders = pcxt->nworkers_launched;
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{
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node->reader = (TupleQueueReader **)
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shm_mq_set_handle(node->pei->tqueue[i],
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palloc(node->nreaders * sizeof(TupleQueueReader *));
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pcxt->worker[i].bgwhandle);
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memcpy(node->reader, node->pei->reader,
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node->reader[node->nreaders++] =
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node->nreaders * sizeof(TupleQueueReader *));
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CreateTupleQueueReader(node->pei->tqueue[i],
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fslot->tts_tupleDescriptor);
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}
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}
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}
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else
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else
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{
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{
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/* No workers? Then never mind. */
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/* No workers? Then never mind. */
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ExecShutdownGatherWorkers(node);
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node->nreaders = 0;
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node->reader = NULL;
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}
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}
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node->nextreader = 0;
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}
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}
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/* Run plan locally if no workers or not single-copy. */
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/* Run plan locally if no workers or not single-copy. */
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node->need_to_scan_locally = (node->reader == NULL)
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node->need_to_scan_locally = (node->nreaders == 0)
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|| !gather->single_copy;
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|| !gather->single_copy;
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node->initialized = true;
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node->initialized = true;
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}
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}
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@ -258,11 +254,11 @@ gather_getnext(GatherState *gatherstate)
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MemoryContext tupleContext = gatherstate->ps.ps_ExprContext->ecxt_per_tuple_memory;
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MemoryContext tupleContext = gatherstate->ps.ps_ExprContext->ecxt_per_tuple_memory;
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HeapTuple tup;
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HeapTuple tup;
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while (gatherstate->reader != NULL || gatherstate->need_to_scan_locally)
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while (gatherstate->nreaders > 0 || gatherstate->need_to_scan_locally)
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{
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{
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CHECK_FOR_INTERRUPTS();
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CHECK_FOR_INTERRUPTS();
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if (gatherstate->reader != NULL)
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if (gatherstate->nreaders > 0)
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{
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{
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MemoryContext oldContext;
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MemoryContext oldContext;
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@ -319,19 +315,15 @@ gather_readnext(GatherState *gatherstate)
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tup = TupleQueueReaderNext(reader, true, &readerdone);
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tup = TupleQueueReaderNext(reader, true, &readerdone);
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/*
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/*
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* If this reader is done, remove it, and collapse the array. If all
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* If this reader is done, remove it from our working array of active
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* readers are done, clean up remaining worker state.
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* readers. If all readers are done, we're outta here.
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*/
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*/
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if (readerdone)
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if (readerdone)
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{
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{
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Assert(!tup);
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Assert(!tup);
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DestroyTupleQueueReader(reader);
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--gatherstate->nreaders;
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--gatherstate->nreaders;
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if (gatherstate->nreaders == 0)
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if (gatherstate->nreaders == 0)
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{
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ExecShutdownGatherWorkers(gatherstate);
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return NULL;
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return NULL;
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}
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memmove(&gatherstate->reader[gatherstate->nextreader],
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memmove(&gatherstate->reader[gatherstate->nextreader],
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&gatherstate->reader[gatherstate->nextreader + 1],
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&gatherstate->reader[gatherstate->nextreader + 1],
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sizeof(TupleQueueReader *)
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sizeof(TupleQueueReader *)
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@ -378,37 +370,25 @@ gather_readnext(GatherState *gatherstate)
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/* ----------------------------------------------------------------
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/* ----------------------------------------------------------------
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* ExecShutdownGatherWorkers
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* ExecShutdownGatherWorkers
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*
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*
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* Destroy the parallel workers. Collect all the stats after
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* Stop all the parallel workers.
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* workers are stopped, else some work done by workers won't be
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* accounted.
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* ----------------------------------------------------------------
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* ----------------------------------------------------------------
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*/
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*/
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static void
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static void
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ExecShutdownGatherWorkers(GatherState *node)
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ExecShutdownGatherWorkers(GatherState *node)
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{
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{
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/* Shut down tuple queue readers before shutting down workers. */
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if (node->reader != NULL)
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{
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int i;
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for (i = 0; i < node->nreaders; ++i)
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DestroyTupleQueueReader(node->reader[i]);
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pfree(node->reader);
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node->reader = NULL;
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}
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/* Now shut down the workers. */
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if (node->pei != NULL)
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if (node->pei != NULL)
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ExecParallelFinish(node->pei);
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ExecParallelFinish(node->pei);
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/* Flush local copy of reader array */
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if (node->reader)
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pfree(node->reader);
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node->reader = NULL;
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}
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}
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/* ----------------------------------------------------------------
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/* ----------------------------------------------------------------
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* ExecShutdownGather
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* ExecShutdownGather
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*
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*
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* Destroy the setup for parallel workers including parallel context.
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* Destroy the setup for parallel workers including parallel context.
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* Collect all the stats after workers are stopped, else some work
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* done by workers won't be accounted.
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* ----------------------------------------------------------------
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* ----------------------------------------------------------------
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*/
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*/
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void
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void
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@ -178,7 +178,6 @@ ExecGatherMerge(PlanState *pstate)
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GatherMergeState *node = castNode(GatherMergeState, pstate);
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GatherMergeState *node = castNode(GatherMergeState, pstate);
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TupleTableSlot *slot;
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TupleTableSlot *slot;
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ExprContext *econtext;
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ExprContext *econtext;
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int i;
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CHECK_FOR_INTERRUPTS();
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CHECK_FOR_INTERRUPTS();
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@ -214,27 +213,23 @@ ExecGatherMerge(PlanState *pstate)
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LaunchParallelWorkers(pcxt);
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LaunchParallelWorkers(pcxt);
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/* We save # workers launched for the benefit of EXPLAIN */
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/* We save # workers launched for the benefit of EXPLAIN */
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node->nworkers_launched = pcxt->nworkers_launched;
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node->nworkers_launched = pcxt->nworkers_launched;
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node->nreaders = 0;
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/* Set up tuple queue readers to read the results. */
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/* Set up tuple queue readers to read the results. */
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if (pcxt->nworkers_launched > 0)
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if (pcxt->nworkers_launched > 0)
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{
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{
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node->reader = palloc(pcxt->nworkers_launched *
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ExecParallelCreateReaders(node->pei, node->tupDesc);
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sizeof(TupleQueueReader *));
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/* Make a working array showing the active readers */
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node->nreaders = pcxt->nworkers_launched;
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for (i = 0; i < pcxt->nworkers_launched; ++i)
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node->reader = (TupleQueueReader **)
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{
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palloc(node->nreaders * sizeof(TupleQueueReader *));
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shm_mq_set_handle(node->pei->tqueue[i],
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memcpy(node->reader, node->pei->reader,
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pcxt->worker[i].bgwhandle);
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node->nreaders * sizeof(TupleQueueReader *));
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node->reader[node->nreaders++] =
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CreateTupleQueueReader(node->pei->tqueue[i],
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node->tupDesc);
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}
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}
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}
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else
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else
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{
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{
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/* No workers? Then never mind. */
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/* No workers? Then never mind. */
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ExecShutdownGatherMergeWorkers(node);
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node->nreaders = 0;
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node->reader = NULL;
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}
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}
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}
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}
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@ -284,8 +279,6 @@ ExecEndGatherMerge(GatherMergeState *node)
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* ExecShutdownGatherMerge
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* ExecShutdownGatherMerge
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*
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*
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* Destroy the setup for parallel workers including parallel context.
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* Destroy the setup for parallel workers including parallel context.
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* Collect all the stats after workers are stopped, else some work
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* done by workers won't be accounted.
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* ----------------------------------------------------------------
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* ----------------------------------------------------------------
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*/
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*/
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void
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void
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@ -304,30 +297,19 @@ ExecShutdownGatherMerge(GatherMergeState *node)
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/* ----------------------------------------------------------------
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/* ----------------------------------------------------------------
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* ExecShutdownGatherMergeWorkers
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* ExecShutdownGatherMergeWorkers
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*
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*
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* Destroy the parallel workers. Collect all the stats after
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* Stop all the parallel workers.
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* workers are stopped, else some work done by workers won't be
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* accounted.
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* ----------------------------------------------------------------
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* ----------------------------------------------------------------
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*/
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*/
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static void
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static void
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ExecShutdownGatherMergeWorkers(GatherMergeState *node)
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ExecShutdownGatherMergeWorkers(GatherMergeState *node)
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{
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{
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/* Shut down tuple queue readers before shutting down workers. */
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if (node->reader != NULL)
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{
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int i;
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for (i = 0; i < node->nreaders; ++i)
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if (node->reader[i])
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DestroyTupleQueueReader(node->reader[i]);
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pfree(node->reader);
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node->reader = NULL;
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}
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/* Now shut down the workers. */
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if (node->pei != NULL)
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if (node->pei != NULL)
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ExecParallelFinish(node->pei);
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ExecParallelFinish(node->pei);
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/* Flush local copy of reader array */
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if (node->reader)
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pfree(node->reader);
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node->reader = NULL;
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}
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}
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/* ----------------------------------------------------------------
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/* ----------------------------------------------------------------
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@ -672,8 +654,6 @@ gather_merge_readnext(GatherMergeState *gm_state, int reader, bool nowait)
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else if (tuple_buffer->done)
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else if (tuple_buffer->done)
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{
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{
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/* Reader is known to be exhausted. */
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/* Reader is known to be exhausted. */
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DestroyTupleQueueReader(gm_state->reader[reader - 1]);
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gm_state->reader[reader - 1] = NULL;
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return false;
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return false;
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}
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}
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else
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else
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@ -651,11 +651,13 @@ CreateTupleQueueReader(shm_mq_handle *handle, TupleDesc tupledesc)
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/*
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/*
|
||||||
* Destroy a tuple queue reader.
|
* Destroy a tuple queue reader.
|
||||||
|
*
|
||||||
|
* Note: cleaning up the underlying shm_mq is the caller's responsibility.
|
||||||
|
* We won't access it here, as it may be detached already.
|
||||||
*/
|
*/
|
||||||
void
|
void
|
||||||
DestroyTupleQueueReader(TupleQueueReader *reader)
|
DestroyTupleQueueReader(TupleQueueReader *reader)
|
||||||
{
|
{
|
||||||
shm_mq_detach(reader->queue);
|
|
||||||
if (reader->typmodmap != NULL)
|
if (reader->typmodmap != NULL)
|
||||||
hash_destroy(reader->typmodmap);
|
hash_destroy(reader->typmodmap);
|
||||||
/* Is it worth trying to free substructure of the remap tree? */
|
/* Is it worth trying to free substructure of the remap tree? */
|
||||||
|
|
|
@ -23,17 +23,21 @@ typedef struct SharedExecutorInstrumentation SharedExecutorInstrumentation;
|
||||||
|
|
||||||
typedef struct ParallelExecutorInfo
|
typedef struct ParallelExecutorInfo
|
||||||
{
|
{
|
||||||
PlanState *planstate;
|
PlanState *planstate; /* plan subtree we're running in parallel */
|
||||||
ParallelContext *pcxt;
|
ParallelContext *pcxt; /* parallel context we're using */
|
||||||
BufferUsage *buffer_usage;
|
BufferUsage *buffer_usage; /* points to bufusage area in DSM */
|
||||||
SharedExecutorInstrumentation *instrumentation;
|
SharedExecutorInstrumentation *instrumentation; /* optional */
|
||||||
shm_mq_handle **tqueue;
|
dsa_area *area; /* points to DSA area in DSM */
|
||||||
dsa_area *area;
|
bool finished; /* set true by ExecParallelFinish */
|
||||||
bool finished;
|
/* These two arrays have pcxt->nworkers_launched entries: */
|
||||||
|
shm_mq_handle **tqueue; /* tuple queues for worker output */
|
||||||
|
struct TupleQueueReader **reader; /* tuple reader/writer support */
|
||||||
} ParallelExecutorInfo;
|
} ParallelExecutorInfo;
|
||||||
|
|
||||||
extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate,
|
extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate,
|
||||||
EState *estate, int nworkers, int64 tuples_needed);
|
EState *estate, int nworkers, int64 tuples_needed);
|
||||||
|
extern void ExecParallelCreateReaders(ParallelExecutorInfo *pei,
|
||||||
|
TupleDesc tupDesc);
|
||||||
extern void ExecParallelFinish(ParallelExecutorInfo *pei);
|
extern void ExecParallelFinish(ParallelExecutorInfo *pei);
|
||||||
extern void ExecParallelCleanup(ParallelExecutorInfo *pei);
|
extern void ExecParallelCleanup(ParallelExecutorInfo *pei);
|
||||||
extern void ExecParallelReinitialize(PlanState *planstate,
|
extern void ExecParallelReinitialize(PlanState *planstate,
|
||||||
|
|
Loading…
Reference in New Issue