From 150bc7fb1e9eacaee5d46852fa464e83e7930aca Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Tue, 22 Nov 2016 20:15:37 -0800 Subject: [PATCH 2/3] Signal when a master backend is doing parallel work. --- src/backend/access/transam/parallel.c | 14 ++++++++------ src/backend/executor/nodeGather.c | 6 ++++++ src/include/access/parallel.h | 20 +++++++++++++++++++- 3 files changed, 33 insertions(+), 7 deletions(-) diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index 59dc394..c038ea1 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -88,12 +88,14 @@ typedef struct FixedParallelState } FixedParallelState; /* - * Our parallel worker number. We initialize this to -1, meaning that we are - * not a parallel worker. In parallel workers, it will be set to a value >= 0 - * and < the number of workers before any user code is invoked; each parallel - * worker will get a different parallel worker number. + * Our parallel worker number. We initialize this to PARALLEL_WORKER_MASTER, + * meaning that we are not a parallel worker. In parallel workers, it will be + * set to a value >= 0 and < the number of workers before any user code is + * invoked; each parallel worker will get a different parallel worker number. + * If the master backend performs parallel work, this will temporarily be set + * to PARALLEL_WORKER_MASTER_PARALLEL while doing so. */ -int ParallelWorkerNumber = -1; +int ParallelWorkerNumber = PARALLEL_WORKER_MASTER; /* Is there a parallel message pending which we need to receive? */ volatile bool ParallelMessagePending = false; @@ -955,7 +957,7 @@ ParallelWorkerMain(Datum main_arg) BackgroundWorkerUnblockSignals(); /* Determine and set our parallel worker number. */ - Assert(ParallelWorkerNumber == -1); + Assert(ParallelWorkerNumber == PARALLEL_WORKER_MASTER); memcpy(&ParallelWorkerNumber, MyBgworkerEntry->bgw_extra, sizeof(int)); /* Set up a memory context and resource owner. */ diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c index 880ca62..c292610 100644 --- a/src/backend/executor/nodeGather.c +++ b/src/backend/executor/nodeGather.c @@ -305,7 +305,13 @@ gather_getnext(GatherState *gatherstate) if (gatherstate->need_to_scan_locally) { + /* + * Signal that the master backend temparily is doing parallel + * work. + */ + ParallelWorkerNumber = PARALLEL_WORKER_MASTER_PARALLEL; outerTupleSlot = ExecProcNode(outerPlan); + ParallelWorkerNumber = PARALLEL_WORKER_MASTER; if (!TupIsNull(outerTupleSlot)) return outerTupleSlot; diff --git a/src/include/access/parallel.h b/src/include/access/parallel.h index 2f8f36f..ce8b6b6 100644 --- a/src/include/access/parallel.h +++ b/src/include/access/parallel.h @@ -50,7 +50,25 @@ extern volatile bool ParallelMessagePending; extern int ParallelWorkerNumber; extern bool InitializingParallelWorker; -#define IsParallelWorker() (ParallelWorkerNumber >= 0) +/* + * Values for ParallelWorkerNumber, values >= 0 are workers backends. + */ +/* master backend */ +#define PARALLEL_WORKER_MASTER -2 +/* master backend, performing parallel work */ +#define PARALLEL_WORKER_MASTER_PARALLEL -1 + +/* Is the process a parallel worker? */ +#define IsParallelWorker() \ + (ParallelWorkerNumber > PARALLEL_WORKER_MASTER_PARALLEL) + +/* + * Is the process performing parallelized work? This can be a the case in a + * worker (in which case IsParallelWorker() would be true), or it can be the + * master backend performing parallel work itself. + */ +#define PerformingParallelWork() \ + (ParallelWorkerNumber > PARALLEL_WORKER_MASTER) extern ParallelContext *CreateParallelContext(parallel_worker_main_type entrypoint, int nworkers); extern ParallelContext *CreateParallelContextForExternalFunction(char *library_name, char *function_name, int nworkers); -- 2.10.2