From d6a149f4e6a1243ccae6e1817050da9e84050b2a Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 30 Aug 2017 13:18:16 -0400 Subject: [PATCH] Separate reinitialization of shared parallel-scan state from ExecReScan. Previously, the parallel executor logic did reinitialization of shared state within the ExecReScan code for parallel-aware scan nodes. This is problematic, because it means that the ExecReScan call has to occur synchronously (ie, during the parent Gather node's ReScan call). That is swimming very much against the tide so far as the ExecReScan machinery is concerned; the fact that it works at all today depends on a lot of fragile assumptions, such as that no plan node between Gather and a parallel-aware scan node is parameterized. Another objection is that because ExecReScan might be called in workers as well as the leader, hacky extra tests are needed in some places to prevent unwanted shared-state resets. Hence, let's separate this code into two functions, a ReInitializeDSM call and the ReScan call proper. ReInitializeDSM is called only in the leader and is guaranteed to run before we start new workers. ReScan is returned to its traditional function of resetting only local state, which means that ExecReScan's usual habits of delaying or eliminating child rescan calls are safe again. As with the preceding commit 7df2c1f8d, it doesn't seem to be necessary to make these changes in 9.6, which is a good thing because the FDW and CustomScan APIs are impacted. Discussion: https://postgr.es/m/CAA4eK1JkByysFJNh9M349u_nNjqETuEnY_y1VUc_kJiU0bxtaQ@mail.gmail.com --- doc/src/sgml/custom-scan.sgml | 29 ++++++-- doc/src/sgml/fdwhandler.sgml | 43 ++++++++---- src/backend/access/heap/heapam.c | 38 +++++----- src/backend/executor/execParallel.c | 85 +++++++++++++++++++---- src/backend/executor/nodeBitmapHeapscan.c | 42 ++++++----- src/backend/executor/nodeCustom.c | 15 ++++ src/backend/executor/nodeForeignscan.c | 23 +++++- src/backend/executor/nodeGather.c | 29 ++++---- src/backend/executor/nodeGatherMerge.c | 29 ++++---- src/backend/executor/nodeIndexonlyscan.c | 29 ++++---- src/backend/executor/nodeIndexscan.c | 38 ++++------ src/backend/executor/nodeSeqscan.c | 16 +++++ src/include/access/heapam.h | 1 + src/include/executor/execParallel.h | 3 +- src/include/executor/nodeBitmapHeapscan.h | 2 + src/include/executor/nodeCustom.h | 2 + src/include/executor/nodeForeignscan.h | 2 + src/include/executor/nodeIndexonlyscan.h | 2 + src/include/executor/nodeIndexscan.h | 1 + src/include/executor/nodeSeqscan.h | 1 + src/include/foreign/fdwapi.h | 4 ++ src/include/nodes/extensible.h | 3 + 22 files changed, 302 insertions(+), 135 deletions(-) diff --git a/doc/src/sgml/custom-scan.sgml b/doc/src/sgml/custom-scan.sgml index 6159c3a24e..9d1ca7bfe1 100644 --- a/doc/src/sgml/custom-scan.sgml +++ b/doc/src/sgml/custom-scan.sgml @@ -320,22 +320,39 @@ void (*InitializeDSMCustomScan) (CustomScanState *node, void *coordinate); Initialize the dynamic shared memory that will be required for parallel - operation; coordinate points to an amount of allocated space - equal to the return value of EstimateDSMCustomScan. + operation. coordinate points to a shared memory area of + size equal to the return value of EstimateDSMCustomScan. This callback is optional, and need only be supplied if this custom scan provider supports parallel execution. +void (*ReInitializeDSMCustomScan) (CustomScanState *node, + ParallelContext *pcxt, + void *coordinate); + + Re-initialize the dynamic shared memory required for parallel operation + when the custom-scan plan node is about to be re-scanned. + This callback is optional, and need only be supplied if this custom + scan provider supports parallel execution. + Recommended practice is that this callback reset only shared state, + while the ReScanCustomScan callback resets only local + state. Currently, this callback will be called + before ReScanCustomScan, but it's best not to rely on + that ordering. + + + + void (*InitializeWorkerCustomScan) (CustomScanState *node, shm_toc *toc, void *coordinate); - Initialize a parallel worker's custom state based on the shared state - set up in the leader by InitializeDSMCustomScan. - This callback is optional, and needs only be supplied if this - custom path supports parallel execution. + Initialize a parallel worker's local state based on the shared state + set up by the leader during InitializeDSMCustomScan. + This callback is optional, and need only be supplied if this custom + scan provider supports parallel execution. diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml index dbeaab555d..cfa6808417 100644 --- a/doc/src/sgml/fdwhandler.sgml +++ b/doc/src/sgml/fdwhandler.sgml @@ -1191,12 +1191,12 @@ ImportForeignSchema (ImportForeignSchemaStmt *stmt, Oid serverOid); A ForeignScan node can, optionally, support parallel execution. A parallel ForeignScan will be executed - in multiple processes and should return each row only once across + in multiple processes and must return each row exactly once across all cooperating processes. To do this, processes can coordinate through - fixed size chunks of dynamic shared memory. This shared memory is not - guaranteed to be mapped at the same address in every process, so pointers - may not be used. The following callbacks are all optional in general, - but required if parallel execution is to be supported. + fixed-size chunks of dynamic shared memory. This shared memory is not + guaranteed to be mapped at the same address in every process, so it + must not contain pointers. The following functions are all optional, + but most are required if parallel execution is to be supported. @@ -1215,7 +1215,7 @@ IsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel, - If this callback is not defined, it is assumed that the scan must take + If this function is not defined, it is assumed that the scan must take place within the parallel leader. Note that returning true does not mean that the scan itself can be done in parallel, only that the scan can be performed within a parallel worker. Therefore, it can be useful to define @@ -1230,6 +1230,9 @@ EstimateDSMForeignScan(ForeignScanState *node, ParallelContext *pcxt); Estimate the amount of dynamic shared memory that will be required for parallel operation. This may be higher than the amount that will actually be used, but it must not be lower. The return value is in bytes. + This function is optional, and can be omitted if not needed; but if it + is omitted, the next three functions must be omitted as well, because + no shared memory will be allocated for the FDW's use. @@ -1239,8 +1242,25 @@ InitializeDSMForeignScan(ForeignScanState *node, ParallelContext *pcxt, void *coordinate); Initialize the dynamic shared memory that will be required for parallel - operation; coordinate points to an amount of allocated space - equal to the return value of EstimateDSMForeignScan. + operation. coordinate points to a shared memory area of + size equal to the return value of EstimateDSMForeignScan. + This function is optional, and can be omitted if not needed. + + + + +void +ReInitializeDSMForeignScan(ForeignScanState *node, ParallelContext *pcxt, + void *coordinate); + + Re-initialize the dynamic shared memory required for parallel operation + when the foreign-scan plan node is about to be re-scanned. + This function is optional, and can be omitted if not needed. + Recommended practice is that this function reset only shared state, + while the ReScanForeignScan function resets only local + state. Currently, this function will be called + before ReScanForeignScan, but it's best not to rely on + that ordering. @@ -1249,10 +1269,9 @@ void InitializeWorkerForeignScan(ForeignScanState *node, shm_toc *toc, void *coordinate); - Initialize a parallel worker's custom state based on the shared state - set up in the leader by InitializeDSMForeignScan. - This callback is optional, and needs only be supplied if this - custom path supports parallel execution. + Initialize a parallel worker's local state based on the shared state + set up by the leader during InitializeDSMForeignScan. + This function is optional, and can be omitted if not needed. diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index e283fe5b1f..e61dd771d0 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1525,25 +1525,6 @@ heap_rescan(HeapScanDesc scan, * reinitialize scan descriptor */ initscan(scan, key, true); - - /* - * reset parallel scan, if present - */ - if (scan->rs_parallel != NULL) - { - ParallelHeapScanDesc parallel_scan; - - /* - * Caller is responsible for making sure that all workers have - * finished the scan before calling this, so it really shouldn't be - * necessary to acquire the mutex at all. We acquire it anyway, just - * to be tidy. - */ - parallel_scan = scan->rs_parallel; - SpinLockAcquire(¶llel_scan->phs_mutex); - parallel_scan->phs_cblock = parallel_scan->phs_startblock; - SpinLockRelease(¶llel_scan->phs_mutex); - } } /* ---------------- @@ -1640,6 +1621,25 @@ heap_parallelscan_initialize(ParallelHeapScanDesc target, Relation relation, SerializeSnapshot(snapshot, target->phs_snapshot_data); } +/* ---------------- + * heap_parallelscan_reinitialize - reset a parallel scan + * + * Call this in the leader process. Caller is responsible for + * making sure that all workers have finished the scan beforehand. + * ---------------- + */ +void +heap_parallelscan_reinitialize(ParallelHeapScanDesc parallel_scan) +{ + /* + * It shouldn't be necessary to acquire the mutex here, but we do it + * anyway, just to be tidy. + */ + SpinLockAcquire(¶llel_scan->phs_mutex); + parallel_scan->phs_cblock = parallel_scan->phs_startblock; + SpinLockRelease(¶llel_scan->phs_mutex); +} + /* ---------------- * heap_beginscan_parallel - join a parallel scan * diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c index ce47f1d4a8..2313b4c45c 100644 --- a/src/backend/executor/execParallel.c +++ b/src/backend/executor/execParallel.c @@ -109,6 +109,8 @@ static bool ExecParallelInitializeDSM(PlanState *node, ExecParallelInitializeDSMContext *d); static shm_mq_handle **ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize); +static bool ExecParallelReInitializeDSM(PlanState *planstate, + ParallelContext *pcxt); static bool ExecParallelRetrieveInstrumentation(PlanState *planstate, SharedExecutorInstrumentation *instrumentation); @@ -364,18 +366,6 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize) return responseq; } -/* - * Re-initialize the parallel executor info such that it can be reused by - * workers. - */ -void -ExecParallelReinitialize(ParallelExecutorInfo *pei) -{ - ReinitializeParallelDSM(pei->pcxt); - pei->tqueue = ExecParallelSetupTupleQueues(pei->pcxt, true); - pei->finished = false; -} - /* * Sets up the required infrastructure for backend workers to perform * execution and return results to the main backend. @@ -567,7 +557,7 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers) ExecParallelInitializeDSM(planstate, &d); /* - * Make sure that the world hasn't shifted under our feat. This could + * Make sure that the world hasn't shifted under our feet. This could * probably just be an Assert(), but let's be conservative for now. */ if (e.nnodes != d.nnodes) @@ -577,6 +567,75 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers) return pei; } +/* + * Re-initialize the parallel executor shared memory state before launching + * a fresh batch of workers. + */ +void +ExecParallelReinitialize(PlanState *planstate, + ParallelExecutorInfo *pei) +{ + /* Old workers must already be shut down */ + Assert(pei->finished); + + ReinitializeParallelDSM(pei->pcxt); + pei->tqueue = ExecParallelSetupTupleQueues(pei->pcxt, true); + pei->finished = false; + + /* Traverse plan tree and let each child node reset associated state. */ + ExecParallelReInitializeDSM(planstate, pei->pcxt); +} + +/* + * Traverse plan tree to reinitialize per-node dynamic shared memory state + */ +static bool +ExecParallelReInitializeDSM(PlanState *planstate, + ParallelContext *pcxt) +{ + if (planstate == NULL) + return false; + + /* + * Call reinitializers for DSM-using plan nodes. + */ + if (planstate->plan->parallel_aware) + { + switch (nodeTag(planstate)) + { + case T_SeqScanState: + ExecSeqScanReInitializeDSM((SeqScanState *) planstate, + pcxt); + break; + case T_IndexScanState: + ExecIndexScanReInitializeDSM((IndexScanState *) planstate, + pcxt); + break; + case T_IndexOnlyScanState: + ExecIndexOnlyScanReInitializeDSM((IndexOnlyScanState *) planstate, + pcxt); + break; + case T_ForeignScanState: + ExecForeignScanReInitializeDSM((ForeignScanState *) planstate, + pcxt); + break; + case T_CustomScanState: + ExecCustomScanReInitializeDSM((CustomScanState *) planstate, + pcxt); + break; + case T_BitmapHeapScanState: + ExecBitmapHeapReInitializeDSM((BitmapHeapScanState *) planstate, + pcxt); + break; + + default: + break; + } + } + + return planstate_tree_walker(planstate, ExecParallelReInitializeDSM, pcxt); +} + /* * Copy instrumentation information about this node and its descendants from * dynamic shared memory. diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index 79f534e4e9..f7e55e0b45 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -705,23 +705,6 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node) node->shared_tbmiterator = NULL; node->shared_prefetch_iterator = NULL; - /* Reset parallel bitmap state, if present */ - if (node->pstate) - { - dsa_area *dsa = node->ss.ps.state->es_query_dsa; - - node->pstate->state = BM_INITIAL; - - if (DsaPointerIsValid(node->pstate->tbmiterator)) - tbm_free_shared_area(dsa, node->pstate->tbmiterator); - - if (DsaPointerIsValid(node->pstate->prefetch_iterator)) - tbm_free_shared_area(dsa, node->pstate->prefetch_iterator); - - node->pstate->tbmiterator = InvalidDsaPointer; - node->pstate->prefetch_iterator = InvalidDsaPointer; - } - ExecScanReScan(&node->ss); /* @@ -999,6 +982,31 @@ ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node, node->pstate = pstate; } +/* ---------------------------------------------------------------- + * ExecBitmapHeapReInitializeDSM + * + * Reset shared state before beginning a fresh scan. + * ---------------------------------------------------------------- + */ +void +ExecBitmapHeapReInitializeDSM(BitmapHeapScanState *node, + ParallelContext *pcxt) +{ + ParallelBitmapHeapState *pstate = node->pstate; + dsa_area *dsa = node->ss.ps.state->es_query_dsa; + + pstate->state = BM_INITIAL; + + if (DsaPointerIsValid(pstate->tbmiterator)) + tbm_free_shared_area(dsa, pstate->tbmiterator); + + if (DsaPointerIsValid(pstate->prefetch_iterator)) + tbm_free_shared_area(dsa, pstate->prefetch_iterator); + + pstate->tbmiterator = InvalidDsaPointer; + pstate->prefetch_iterator = InvalidDsaPointer; +} + /* ---------------------------------------------------------------- * ExecBitmapHeapInitializeWorker * diff --git a/src/backend/executor/nodeCustom.c b/src/backend/executor/nodeCustom.c index fb7645b1f4..07dcabef55 100644 --- a/src/backend/executor/nodeCustom.c +++ b/src/backend/executor/nodeCustom.c @@ -194,6 +194,21 @@ ExecCustomScanInitializeDSM(CustomScanState *node, ParallelContext *pcxt) } } +void +ExecCustomScanReInitializeDSM(CustomScanState *node, ParallelContext *pcxt) +{ + const CustomExecMethods *methods = node->methods; + + if (methods->ReInitializeDSMCustomScan) + { + int plan_node_id = node->ss.ps.plan->plan_node_id; + void *coordinate; + + coordinate = shm_toc_lookup(pcxt->toc, plan_node_id, false); + methods->ReInitializeDSMCustomScan(node, pcxt, coordinate); + } +} + void ExecCustomScanInitializeWorker(CustomScanState *node, shm_toc *toc) { diff --git a/src/backend/executor/nodeForeignscan.c b/src/backend/executor/nodeForeignscan.c index 140e82ef5e..20892d6d5f 100644 --- a/src/backend/executor/nodeForeignscan.c +++ b/src/backend/executor/nodeForeignscan.c @@ -332,7 +332,28 @@ ExecForeignScanInitializeDSM(ForeignScanState *node, ParallelContext *pcxt) } /* ---------------------------------------------------------------- - * ExecForeignScanInitializeDSM + * ExecForeignScanReInitializeDSM + * + * Reset shared state before beginning a fresh scan. + * ---------------------------------------------------------------- + */ +void +ExecForeignScanReInitializeDSM(ForeignScanState *node, ParallelContext *pcxt) +{ + FdwRoutine *fdwroutine = node->fdwroutine; + + if (fdwroutine->ReInitializeDSMForeignScan) + { + int plan_node_id = node->ss.ps.plan->plan_node_id; + void *coordinate; + + coordinate = shm_toc_lookup(pcxt->toc, plan_node_id, false); + fdwroutine->ReInitializeDSMForeignScan(node, pcxt, coordinate); + } +} + +/* ---------------------------------------------------------------- + * ExecForeignScanInitializeWorker * * Initialization according to the parallel coordination information * ---------------------------------------------------------------- diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c index 3aa819f450..55fce231ce 100644 --- a/src/backend/executor/nodeGather.c +++ b/src/backend/executor/nodeGather.c @@ -152,11 +152,14 @@ ExecGather(PlanState *pstate) { ParallelContext *pcxt; - /* Initialize the workers required to execute Gather node. */ + /* Initialize, or re-initialize, shared state needed by workers. */ if (!node->pei) node->pei = ExecInitParallelPlan(node->ps.lefttree, estate, gather->num_workers); + else + ExecParallelReinitialize(node->ps.lefttree, + node->pei); /* * Register backend workers. We might not get as many as we @@ -424,7 +427,7 @@ ExecShutdownGather(GatherState *node) /* ---------------------------------------------------------------- * ExecReScanGather * - * Re-initialize the workers and rescans a relation via them. + * Prepare to re-scan the result of a Gather. * ---------------------------------------------------------------- */ void @@ -433,19 +436,12 @@ ExecReScanGather(GatherState *node) Gather *gather = (Gather *) node->ps.plan; PlanState *outerPlan = outerPlanState(node); - /* - * Re-initialize the parallel workers to perform rescan of relation. We - * want to gracefully shutdown all the workers so that they should be able - * to propagate any error or other information to master backend before - * dying. Parallel context will be reused for rescan. - */ + /* Make sure any existing workers are gracefully shut down */ ExecShutdownGatherWorkers(node); + /* Mark node so that shared state will be rebuilt at next call */ node->initialized = false; - if (node->pei) - ExecParallelReinitialize(node->pei); - /* * Set child node's chgParam to tell it that the next scan might deliver a * different set of rows within the leader process. (The overall rowset @@ -457,10 +453,15 @@ ExecReScanGather(GatherState *node) outerPlan->chgParam = bms_add_member(outerPlan->chgParam, gather->rescan_param); - /* - * if chgParam of subnode is not null then plan will be re-scanned by - * first ExecProcNode. + * If chgParam of subnode is not null then plan will be re-scanned by + * first ExecProcNode. Note: because this does nothing if we have a + * rescan_param, it's currently guaranteed that parallel-aware child nodes + * will not see a ReScan call until after they get a ReInitializeDSM call. + * That ordering might not be something to rely on, though. A good rule + * of thumb is that ReInitializeDSM should reset only shared state, ReScan + * should reset only local state, and anything that depends on both of + * those steps being finished must wait until the first ExecProcNode call. */ if (outerPlan->chgParam == NULL) ExecReScan(outerPlan); diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c index e8c70dfc60..90c1be96ef 100644 --- a/src/backend/executor/nodeGatherMerge.c +++ b/src/backend/executor/nodeGatherMerge.c @@ -186,11 +186,14 @@ ExecGatherMerge(PlanState *pstate) { ParallelContext *pcxt; - /* Initialize data structures for workers. */ + /* Initialize, or re-initialize, shared state needed by workers. */ if (!node->pei) node->pei = ExecInitParallelPlan(node->ps.lefttree, estate, gm->num_workers); + else + ExecParallelReinitialize(node->ps.lefttree, + node->pei); /* Try to launch workers. */ pcxt = node->pei->pcxt; @@ -319,7 +322,7 @@ ExecShutdownGatherMergeWorkers(GatherMergeState *node) /* ---------------------------------------------------------------- * ExecReScanGatherMerge * - * Re-initialize the workers and rescans a relation via them. + * Prepare to re-scan the result of a GatherMerge. * ---------------------------------------------------------------- */ void @@ -328,20 +331,13 @@ ExecReScanGatherMerge(GatherMergeState *node) GatherMerge *gm = (GatherMerge *) node->ps.plan; PlanState *outerPlan = outerPlanState(node); - /* - * Re-initialize the parallel workers to perform rescan of relation. We - * want to gracefully shutdown all the workers so that they should be able - * to propagate any error or other information to master backend before - * dying. Parallel context will be reused for rescan. - */ + /* Make sure any existing workers are gracefully shut down */ ExecShutdownGatherMergeWorkers(node); + /* Mark node so that shared state will be rebuilt at next call */ node->initialized = false; node->gm_initialized = false; - if (node->pei) - ExecParallelReinitialize(node->pei); - /* * Set child node's chgParam to tell it that the next scan might deliver a * different set of rows within the leader process. (The overall rowset @@ -353,10 +349,15 @@ ExecReScanGatherMerge(GatherMergeState *node) outerPlan->chgParam = bms_add_member(outerPlan->chgParam, gm->rescan_param); - /* - * if chgParam of subnode is not null then plan will be re-scanned by - * first ExecProcNode. + * If chgParam of subnode is not null then plan will be re-scanned by + * first ExecProcNode. Note: because this does nothing if we have a + * rescan_param, it's currently guaranteed that parallel-aware child nodes + * will not see a ReScan call until after they get a ReInitializeDSM call. + * That ordering might not be something to rely on, though. A good rule + * of thumb is that ReInitializeDSM should reset only shared state, ReScan + * should reset only local state, and anything that depends on both of + * those steps being finished must wait until the first ExecProcNode call. */ if (outerPlan->chgParam == NULL) ExecReScan(outerPlan); diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c index fe7ba3f1a4..5351cb8981 100644 --- a/src/backend/executor/nodeIndexonlyscan.c +++ b/src/backend/executor/nodeIndexonlyscan.c @@ -25,6 +25,7 @@ * parallel index-only scan * ExecIndexOnlyScanInitializeDSM initialize DSM for parallel * index-only scan + * ExecIndexOnlyScanReInitializeDSM reinitialize DSM for fresh scan * ExecIndexOnlyScanInitializeWorker attach to DSM info in parallel worker */ #include "postgres.h" @@ -336,16 +337,6 @@ ExecIndexOnlyScan(PlanState *pstate) void ExecReScanIndexOnlyScan(IndexOnlyScanState *node) { - bool reset_parallel_scan = true; - - /* - * If we are here to just update the scan keys, then don't reset parallel - * scan. For detailed reason behind this look in the comments for - * ExecReScanIndexScan. - */ - if (node->ioss_NumRuntimeKeys != 0 && !node->ioss_RuntimeKeysReady) - reset_parallel_scan = false; - /* * If we are doing runtime key calculations (ie, any of the index key * values weren't simple Consts), compute the new key values. But first, @@ -366,15 +357,10 @@ ExecReScanIndexOnlyScan(IndexOnlyScanState *node) /* reset index scan */ if (node->ioss_ScanDesc) - { - index_rescan(node->ioss_ScanDesc, node->ioss_ScanKeys, node->ioss_NumScanKeys, node->ioss_OrderByKeys, node->ioss_NumOrderByKeys); - if (reset_parallel_scan && node->ioss_ScanDesc->parallel_scan) - index_parallelrescan(node->ioss_ScanDesc); - } ExecScanReScan(&node->ss); } @@ -671,6 +657,19 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node, node->ioss_OrderByKeys, node->ioss_NumOrderByKeys); } +/* ---------------------------------------------------------------- + * ExecIndexOnlyScanReInitializeDSM + * + * Reset shared state before beginning a fresh scan. + * ---------------------------------------------------------------- + */ +void +ExecIndexOnlyScanReInitializeDSM(IndexOnlyScanState *node, + ParallelContext *pcxt) +{ + index_parallelrescan(node->ioss_ScanDesc); +} + /* ---------------------------------------------------------------- * ExecIndexOnlyScanInitializeWorker * diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c index 404076d593..638b17b07c 100644 --- a/src/backend/executor/nodeIndexscan.c +++ b/src/backend/executor/nodeIndexscan.c @@ -24,6 +24,7 @@ * ExecIndexRestrPos restores scan position. * ExecIndexScanEstimate estimates DSM space needed for parallel index scan * ExecIndexScanInitializeDSM initialize DSM for parallel indexscan + * ExecIndexScanReInitializeDSM reinitialize DSM for fresh scan * ExecIndexScanInitializeWorker attach to DSM info in parallel worker */ #include "postgres.h" @@ -577,18 +578,6 @@ ExecIndexScan(PlanState *pstate) void ExecReScanIndexScan(IndexScanState *node) { - bool reset_parallel_scan = true; - - /* - * If we are here to just update the scan keys, then don't reset parallel - * scan. We don't want each of the participating process in the parallel - * scan to update the shared parallel scan state at the start of the scan. - * It is quite possible that one of the participants has already begun - * scanning the index when another has yet to start it. - */ - if (node->iss_NumRuntimeKeys != 0 && !node->iss_RuntimeKeysReady) - reset_parallel_scan = false; - /* * If we are doing runtime key calculations (ie, any of the index key * values weren't simple Consts), compute the new key values. But first, @@ -614,21 +603,11 @@ ExecReScanIndexScan(IndexScanState *node) reorderqueue_pop(node); } - /* - * Reset (parallel) index scan. For parallel-aware nodes, the scan - * descriptor is initialized during actual execution of node and we can - * reach here before that (ex. during execution of nest loop join). So, - * avoid updating the scan descriptor at that time. - */ + /* reset index scan */ if (node->iss_ScanDesc) - { index_rescan(node->iss_ScanDesc, node->iss_ScanKeys, node->iss_NumScanKeys, node->iss_OrderByKeys, node->iss_NumOrderByKeys); - - if (reset_parallel_scan && node->iss_ScanDesc->parallel_scan) - index_parallelrescan(node->iss_ScanDesc); - } node->iss_ReachedEnd = false; ExecScanReScan(&node->ss); @@ -1716,6 +1695,19 @@ ExecIndexScanInitializeDSM(IndexScanState *node, node->iss_OrderByKeys, node->iss_NumOrderByKeys); } +/* ---------------------------------------------------------------- + * ExecIndexScanReInitializeDSM + * + * Reset shared state before beginning a fresh scan. + * ---------------------------------------------------------------- + */ +void +ExecIndexScanReInitializeDSM(IndexScanState *node, + ParallelContext *pcxt) +{ + index_parallelrescan(node->iss_ScanDesc); +} + /* ---------------------------------------------------------------- * ExecIndexScanInitializeWorker * diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c index 5c49d4ca8a..d4ac939c9b 100644 --- a/src/backend/executor/nodeSeqscan.c +++ b/src/backend/executor/nodeSeqscan.c @@ -22,6 +22,7 @@ * * ExecSeqScanEstimate estimates DSM space needed for parallel scan * ExecSeqScanInitializeDSM initialize DSM for parallel scan + * ExecSeqScanReInitializeDSM reinitialize DSM for fresh parallel scan * ExecSeqScanInitializeWorker attach to DSM info in parallel worker */ #include "postgres.h" @@ -324,6 +325,21 @@ ExecSeqScanInitializeDSM(SeqScanState *node, heap_beginscan_parallel(node->ss.ss_currentRelation, pscan); } +/* ---------------------------------------------------------------- + * ExecSeqScanReInitializeDSM + * + * Reset shared state before beginning a fresh scan. + * ---------------------------------------------------------------- + */ +void +ExecSeqScanReInitializeDSM(SeqScanState *node, + ParallelContext *pcxt) +{ + HeapScanDesc scan = node->ss.ss_currentScanDesc; + + heap_parallelscan_reinitialize(scan->rs_parallel); +} + /* ---------------------------------------------------------------- * ExecSeqScanInitializeWorker * diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index b2132e723e..4e41024e92 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -130,6 +130,7 @@ extern HeapTuple heap_getnext(HeapScanDesc scan, ScanDirection direction); extern Size heap_parallelscan_estimate(Snapshot snapshot); extern void heap_parallelscan_initialize(ParallelHeapScanDesc target, Relation relation, Snapshot snapshot); +extern void heap_parallelscan_reinitialize(ParallelHeapScanDesc parallel_scan); extern HeapScanDesc heap_beginscan_parallel(Relation, ParallelHeapScanDesc); extern bool heap_fetch(Relation relation, Snapshot snapshot, diff --git a/src/include/executor/execParallel.h b/src/include/executor/execParallel.h index bd0a87fa04..a6512245b1 100644 --- a/src/include/executor/execParallel.h +++ b/src/include/executor/execParallel.h @@ -36,7 +36,8 @@ extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers); extern void ExecParallelFinish(ParallelExecutorInfo *pei); extern void ExecParallelCleanup(ParallelExecutorInfo *pei); -extern void ExecParallelReinitialize(ParallelExecutorInfo *pei); +extern void ExecParallelReinitialize(PlanState *planstate, + ParallelExecutorInfo *pei); extern void ParallelQueryMain(dsm_segment *seg, shm_toc *toc); diff --git a/src/include/executor/nodeBitmapHeapscan.h b/src/include/executor/nodeBitmapHeapscan.h index c77694cf22..10844a405a 100644 --- a/src/include/executor/nodeBitmapHeapscan.h +++ b/src/include/executor/nodeBitmapHeapscan.h @@ -24,6 +24,8 @@ extern void ExecBitmapHeapEstimate(BitmapHeapScanState *node, ParallelContext *pcxt); extern void ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node, ParallelContext *pcxt); +extern void ExecBitmapHeapReInitializeDSM(BitmapHeapScanState *node, + ParallelContext *pcxt); extern void ExecBitmapHeapInitializeWorker(BitmapHeapScanState *node, shm_toc *toc); diff --git a/src/include/executor/nodeCustom.h b/src/include/executor/nodeCustom.h index a1cc63ae1f..25767b6a4a 100644 --- a/src/include/executor/nodeCustom.h +++ b/src/include/executor/nodeCustom.h @@ -34,6 +34,8 @@ extern void ExecCustomScanEstimate(CustomScanState *node, ParallelContext *pcxt); extern void ExecCustomScanInitializeDSM(CustomScanState *node, ParallelContext *pcxt); +extern void ExecCustomScanReInitializeDSM(CustomScanState *node, + ParallelContext *pcxt); extern void ExecCustomScanInitializeWorker(CustomScanState *node, shm_toc *toc); extern void ExecShutdownCustomScan(CustomScanState *node); diff --git a/src/include/executor/nodeForeignscan.h b/src/include/executor/nodeForeignscan.h index 0b662597d8..0354c2c430 100644 --- a/src/include/executor/nodeForeignscan.h +++ b/src/include/executor/nodeForeignscan.h @@ -25,6 +25,8 @@ extern void ExecForeignScanEstimate(ForeignScanState *node, ParallelContext *pcxt); extern void ExecForeignScanInitializeDSM(ForeignScanState *node, ParallelContext *pcxt); +extern void ExecForeignScanReInitializeDSM(ForeignScanState *node, + ParallelContext *pcxt); extern void ExecForeignScanInitializeWorker(ForeignScanState *node, shm_toc *toc); extern void ExecShutdownForeignScan(ForeignScanState *node); diff --git a/src/include/executor/nodeIndexonlyscan.h b/src/include/executor/nodeIndexonlyscan.h index c8a709c26e..690b5dbfe5 100644 --- a/src/include/executor/nodeIndexonlyscan.h +++ b/src/include/executor/nodeIndexonlyscan.h @@ -28,6 +28,8 @@ extern void ExecIndexOnlyScanEstimate(IndexOnlyScanState *node, ParallelContext *pcxt); extern void ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node, ParallelContext *pcxt); +extern void ExecIndexOnlyScanReInitializeDSM(IndexOnlyScanState *node, + ParallelContext *pcxt); extern void ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node, shm_toc *toc); diff --git a/src/include/executor/nodeIndexscan.h b/src/include/executor/nodeIndexscan.h index 1668e347ee..0670e87e39 100644 --- a/src/include/executor/nodeIndexscan.h +++ b/src/include/executor/nodeIndexscan.h @@ -24,6 +24,7 @@ extern void ExecIndexRestrPos(IndexScanState *node); extern void ExecReScanIndexScan(IndexScanState *node); extern void ExecIndexScanEstimate(IndexScanState *node, ParallelContext *pcxt); extern void ExecIndexScanInitializeDSM(IndexScanState *node, ParallelContext *pcxt); +extern void ExecIndexScanReInitializeDSM(IndexScanState *node, ParallelContext *pcxt); extern void ExecIndexScanInitializeWorker(IndexScanState *node, shm_toc *toc); /* diff --git a/src/include/executor/nodeSeqscan.h b/src/include/executor/nodeSeqscan.h index 0fba79f8de..eb96799cad 100644 --- a/src/include/executor/nodeSeqscan.h +++ b/src/include/executor/nodeSeqscan.h @@ -24,6 +24,7 @@ extern void ExecReScanSeqScan(SeqScanState *node); /* parallel scan support */ extern void ExecSeqScanEstimate(SeqScanState *node, ParallelContext *pcxt); extern void ExecSeqScanInitializeDSM(SeqScanState *node, ParallelContext *pcxt); +extern void ExecSeqScanReInitializeDSM(SeqScanState *node, ParallelContext *pcxt); extern void ExecSeqScanInitializeWorker(SeqScanState *node, shm_toc *toc); #endif /* NODESEQSCAN_H */ diff --git a/src/include/foreign/fdwapi.h b/src/include/foreign/fdwapi.h index e391f20fb8..ef0fbe6f9c 100644 --- a/src/include/foreign/fdwapi.h +++ b/src/include/foreign/fdwapi.h @@ -148,6 +148,9 @@ typedef Size (*EstimateDSMForeignScan_function) (ForeignScanState *node, typedef void (*InitializeDSMForeignScan_function) (ForeignScanState *node, ParallelContext *pcxt, void *coordinate); +typedef void (*ReInitializeDSMForeignScan_function) (ForeignScanState *node, + ParallelContext *pcxt, + void *coordinate); typedef void (*InitializeWorkerForeignScan_function) (ForeignScanState *node, shm_toc *toc, void *coordinate); @@ -224,6 +227,7 @@ typedef struct FdwRoutine IsForeignScanParallelSafe_function IsForeignScanParallelSafe; EstimateDSMForeignScan_function EstimateDSMForeignScan; InitializeDSMForeignScan_function InitializeDSMForeignScan; + ReInitializeDSMForeignScan_function ReInitializeDSMForeignScan; InitializeWorkerForeignScan_function InitializeWorkerForeignScan; ShutdownForeignScan_function ShutdownForeignScan; } FdwRoutine; diff --git a/src/include/nodes/extensible.h b/src/include/nodes/extensible.h index 7325bf536a..0654e79c7b 100644 --- a/src/include/nodes/extensible.h +++ b/src/include/nodes/extensible.h @@ -136,6 +136,9 @@ typedef struct CustomExecMethods void (*InitializeDSMCustomScan) (CustomScanState *node, ParallelContext *pcxt, void *coordinate); + void (*ReInitializeDSMCustomScan) (CustomScanState *node, + ParallelContext *pcxt, + void *coordinate); void (*InitializeWorkerCustomScan) (CustomScanState *node, shm_toc *toc, void *coordinate); -- 2.40.0