greenplumn execParallel 源码
greenplumn execParallel 代码
文件路径：/src/backend/executor/execParallel.c
/*-------------------------------------------------------------------------
*
* execParallel.c
* Support routines for parallel execution.
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* This file contains routines that are intended to support setting up,
* using, and tearing down a ParallelContext from within the PostgreSQL
* executor. The ParallelContext machinery will handle starting the
* workers and ensuring that their state generally matches that of the
* leader; see src/backend/access/transam/README.parallel for details.
* However, we must save and restore relevant executor state, such as
* any ParamListInfo associated with the query, buffer usage info, and
* the actual plan to be passed down to the worker.
*
* IDENTIFICATION
* src/backend/executor/execParallel.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "executor/execParallel.h"
#include "executor/executor.h"
#include "executor/nodeAppend.h"
#include "executor/nodeBitmapHeapscan.h"
#include "executor/nodeCustom.h"
#include "executor/nodeForeignscan.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeSeqscan.h"
#include "executor/nodeSort.h"
#include "executor/nodeSubplan.h"
#include "executor/tqueue.h"
#include "jit/jit.h"
#include "nodes/nodeFuncs.h"
#include "storage/spin.h"
#include "tcop/tcopprot.h"
#include "utils/datum.h"
#include "utils/dsa.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"
#include "pgstat.h"
/*
* Magic numbers for parallel executor communication. We use constants
* greater than any 32-bit integer here so that values < 2^32 can be used
* by individual parallel nodes to store their own state.
*/
#define PARALLEL_KEY_EXECUTOR_FIXED UINT64CONST(0xE000000000000001)
#define PARALLEL_KEY_PLANNEDSTMT UINT64CONST(0xE000000000000002)
#define PARALLEL_KEY_PARAMLISTINFO UINT64CONST(0xE000000000000003)
#define PARALLEL_KEY_BUFFER_USAGE UINT64CONST(0xE000000000000004)
#define PARALLEL_KEY_TUPLE_QUEUE UINT64CONST(0xE000000000000005)
#define PARALLEL_KEY_INSTRUMENTATION UINT64CONST(0xE000000000000006)
#define PARALLEL_KEY_DSA UINT64CONST(0xE000000000000007)
#define PARALLEL_KEY_QUERY_TEXT UINT64CONST(0xE000000000000008)
#define PARALLEL_KEY_JIT_INSTRUMENTATION UINT64CONST(0xE000000000000009)
#define PARALLEL_TUPLE_QUEUE_SIZE 65536
/*
* Fixed-size random stuff that we need to pass to parallel workers.
*/
typedef struct FixedParallelExecutorState
{
int64 tuples_needed; /* tuple bound, see ExecSetTupleBound */
dsa_pointer param_exec;
int eflags;
int jit_flags;
} FixedParallelExecutorState;
/*
* DSM structure for accumulating per-PlanState instrumentation.
*
* instrument_options: Same meaning here as in instrument.c.
*
* instrument_offset: Offset, relative to the start of this structure,
* of the first Instrumentation object. This will depend on the length of
* the plan_node_id array.
*
* num_workers: Number of workers.
*
* num_plan_nodes: Number of plan nodes.
*
* plan_node_id: Array of plan nodes for which we are gathering instrumentation
* from parallel workers. The length of this array is given by num_plan_nodes.
*/
struct SharedExecutorInstrumentation
{
int instrument_options;
int instrument_offset;
int num_workers;
int num_plan_nodes;
int plan_node_id[FLEXIBLE_ARRAY_MEMBER];
/* array of num_plan_nodes * num_workers Instrumentation objects follows */
};
#define GetInstrumentationArray(sei) \
(AssertVariableIsOfTypeMacro(sei, SharedExecutorInstrumentation *), \
(Instrumentation *) (((char *) sei) + sei->instrument_offset))
/* Context object for ExecParallelEstimate. */
typedef struct ExecParallelEstimateContext
{
ParallelContext *pcxt;
int nnodes;
} ExecParallelEstimateContext;
/* Context object for ExecParallelInitializeDSM. */
typedef struct ExecParallelInitializeDSMContext
{
ParallelContext *pcxt;
SharedExecutorInstrumentation *instrumentation;
int nnodes;
} ExecParallelInitializeDSMContext;
/* Helper functions that run in the parallel leader. */
static char *ExecSerializePlan(Plan *plan, EState *estate);
static bool ExecParallelEstimate(PlanState *node,
ExecParallelEstimateContext *e);
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);
/* Helper function that runs in the parallel worker. */
static DestReceiver *ExecParallelGetReceiver(dsm_segment *seg, shm_toc *toc);
/*
* Create a serialized representation of the plan to be sent to each worker.
*/
static char *
ExecSerializePlan(Plan *plan, EState *estate)
{
PlannedStmt *pstmt;
ListCell *lc;
/* We can't scribble on the original plan, so make a copy. */
plan = copyObject(plan);
/*
* The worker will start its own copy of the executor, and that copy will
* insert a junk filter if the toplevel node has any resjunk entries. We
* don't want that to happen, because while resjunk columns shouldn't be
* sent back to the user, here the tuples are coming back to another
* backend which may very well need them. So mutate the target list
* accordingly. This is sort of a hack; there might be better ways to do
* this...
*/
foreach(lc, plan->targetlist)
{
TargetEntry *tle = lfirst_node(TargetEntry, lc);
tle->resjunk = false;
}
/*
* Create a dummy PlannedStmt. Most of the fields don't need to be valid
* for our purposes, but the worker will need at least a minimal
* PlannedStmt to start the executor.
*/
pstmt = makeNode(PlannedStmt);
pstmt->commandType = CMD_SELECT;
pstmt->queryId = UINT64CONST(0);
pstmt->hasReturning = false;
pstmt->hasModifyingCTE = false;
pstmt->canSetTag = true;
pstmt->transientPlan = false;
pstmt->dependsOnRole = false;
pstmt->parallelModeNeeded = false;
pstmt->planTree = plan;
pstmt->rtable = estate->es_range_table;
pstmt->resultRelations = NIL;
/*
* Transfer only parallel-safe subplans, leaving a NULL "hole" in the list
* for unsafe ones (so that the list indexes of the safe ones are
* preserved). This positively ensures that the worker won't try to run,
* or even do ExecInitNode on, an unsafe subplan. That's important to
* protect, eg, non-parallel-aware FDWs from getting into trouble.
*/
pstmt->subplans = NIL;
foreach(lc, estate->es_plannedstmt->subplans)
{
Plan *subplan = (Plan *) lfirst(lc);
if (subplan && !subplan->parallel_safe)
subplan = NULL;
pstmt->subplans = lappend(pstmt->subplans, subplan);
}
pstmt->rewindPlanIDs = NULL;
pstmt->rowMarks = NIL;
pstmt->relationOids = NIL;
pstmt->invalItems = NIL; /* workers can't replan anyway... */
pstmt->paramExecTypes = estate->es_plannedstmt->paramExecTypes;
pstmt->utilityStmt = NULL;
pstmt->stmt_location = -1;
pstmt->stmt_len = -1;
/* Return serialized copy of our dummy PlannedStmt. */
return nodeToString(pstmt);
}
/*
* Parallel-aware plan nodes (and occasionally others) may need some state
* which is shared across all parallel workers. Before we size the DSM, give
* them a chance to call shm_toc_estimate_chunk or shm_toc_estimate_keys on
* &pcxt->estimator.
*
* While we're at it, count the number of PlanState nodes in the tree, so
* we know how many Instrumentation structures we need.
*/
static bool
ExecParallelEstimate(PlanState *planstate, ExecParallelEstimateContext *e)
{
if (planstate == NULL)
return false;
/* Count this node. */
e->nnodes++;
switch (nodeTag(planstate))
{
case T_SeqScanState:
if (planstate->plan->parallel_aware)
ExecSeqScanEstimate((SeqScanState *) planstate,
e->pcxt);
break;
case T_IndexScanState:
if (planstate->plan->parallel_aware)
ExecIndexScanEstimate((IndexScanState *) planstate,
e->pcxt);
break;
case T_IndexOnlyScanState:
if (planstate->plan->parallel_aware)
ExecIndexOnlyScanEstimate((IndexOnlyScanState *) planstate,
e->pcxt);
break;
case T_ForeignScanState:
if (planstate->plan->parallel_aware)
ExecForeignScanEstimate((ForeignScanState *) planstate,
e->pcxt);
break;
case T_AppendState:
if (planstate->plan->parallel_aware)
ExecAppendEstimate((AppendState *) planstate,
e->pcxt);
break;
case T_CustomScanState:
if (planstate->plan->parallel_aware)
ExecCustomScanEstimate((CustomScanState *) planstate,
e->pcxt);
break;
case T_BitmapHeapScanState:
if (planstate->plan->parallel_aware)
ExecBitmapHeapEstimate((BitmapHeapScanState *) planstate,
e->pcxt);
break;
case T_HashJoinState:
if (planstate->plan->parallel_aware)
ExecHashJoinEstimate((HashJoinState *) planstate,
e->pcxt);
break;
case T_HashState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecHashEstimate((HashState *) planstate, e->pcxt);
break;
case T_SortState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortEstimate((SortState *) planstate, e->pcxt);
break;
default:
break;
}
return planstate_tree_walker(planstate, ExecParallelEstimate, e);
}
/*
* Estimate the amount of space required to serialize the indicated parameters.
*/
static Size
EstimateParamExecSpace(EState *estate, Bitmapset *params)
{
int paramid;
Size sz = sizeof(int);
paramid = -1;
while ((paramid = bms_next_member(params, paramid)) >= 0)
{
Oid typeOid;
int16 typLen;
bool typByVal;
ParamExecData *prm;
prm = &(estate->es_param_exec_vals[paramid]);
typeOid = list_nth_oid(estate->es_plannedstmt->paramExecTypes,
paramid);
sz = add_size(sz, sizeof(int)); /* space for paramid */
/* space for datum/isnull */
if (OidIsValid(typeOid))
get_typlenbyval(typeOid, &typLen, &typByVal);
else
{
/* If no type OID, assume by-value, like copyParamList does. */
typLen = sizeof(Datum);
typByVal = true;
}
sz = add_size(sz,
datumEstimateSpace(prm->value, prm->isnull,
typByVal, typLen));
}
return sz;
}
/*
* Serialize specified PARAM_EXEC parameters.
*
* We write the number of parameters first, as a 4-byte integer, and then
* write details for each parameter in turn. The details for each parameter
* consist of a 4-byte paramid (location of param in execution time internal
* parameter array) and then the datum as serialized by datumSerialize().
*/
static dsa_pointer
SerializeParamExecParams(EState *estate, Bitmapset *params, dsa_area *area)
{
Size size;
int nparams;
int paramid;
ParamExecData *prm;
dsa_pointer handle;
char *start_address;
/* Allocate enough space for the current parameter values. */
size = EstimateParamExecSpace(estate, params);
handle = dsa_allocate(area, size);
start_address = dsa_get_address(area, handle);
/* First write the number of parameters as a 4-byte integer. */
nparams = bms_num_members(params);
memcpy(start_address, &nparams, sizeof(int));
start_address += sizeof(int);
/* Write details for each parameter in turn. */
paramid = -1;
while ((paramid = bms_next_member(params, paramid)) >= 0)
{
Oid typeOid;
int16 typLen;
bool typByVal;
prm = &(estate->es_param_exec_vals[paramid]);
typeOid = list_nth_oid(estate->es_plannedstmt->paramExecTypes,
paramid);
/* Write paramid. */
memcpy(start_address, ¶mid, sizeof(int));
start_address += sizeof(int);
/* Write datum/isnull */
if (OidIsValid(typeOid))
get_typlenbyval(typeOid, &typLen, &typByVal);
else
{
/* If no type OID, assume by-value, like copyParamList does. */
typLen = sizeof(Datum);
typByVal = true;
}
datumSerialize(prm->value, prm->isnull, typByVal, typLen,
&start_address);
}
return handle;
}
/*
* Restore specified PARAM_EXEC parameters.
*/
static void
RestoreParamExecParams(char *start_address, EState *estate)
{
int nparams;
int i;
int paramid;
memcpy(&nparams, start_address, sizeof(int));
start_address += sizeof(int);
for (i = 0; i < nparams; i++)
{
ParamExecData *prm;
/* Read paramid */
memcpy(¶mid, start_address, sizeof(int));
start_address += sizeof(int);
prm = &(estate->es_param_exec_vals[paramid]);
/* Read datum/isnull. */
prm->value = datumRestore(&start_address, &prm->isnull);
prm->execPlan = NULL;
}
}
/*
* Initialize the dynamic shared memory segment that will be used to control
* parallel execution.
*/
static bool
ExecParallelInitializeDSM(PlanState *planstate,
ExecParallelInitializeDSMContext *d)
{
if (planstate == NULL)
return false;
/* If instrumentation is enabled, initialize slot for this node. */
if (d->instrumentation != NULL)
d->instrumentation->plan_node_id[d->nnodes] =
planstate->plan->plan_node_id;
/* Count this node. */
d->nnodes++;
/*
* Call initializers for DSM-using plan nodes.
*
* Most plan nodes won't do anything here, but plan nodes that allocated
* DSM may need to initialize shared state in the DSM before parallel
* workers are launched. They can allocate the space they previously
* estimated using shm_toc_allocate, and add the keys they previously
* estimated using shm_toc_insert, in each case targeting pcxt->toc.
*/
switch (nodeTag(planstate))
{
case T_SeqScanState:
if (planstate->plan->parallel_aware)
ExecSeqScanInitializeDSM((SeqScanState *) planstate,
d->pcxt);
break;
case T_IndexScanState:
if (planstate->plan->parallel_aware)
ExecIndexScanInitializeDSM((IndexScanState *) planstate,
d->pcxt);
break;
case T_IndexOnlyScanState:
if (planstate->plan->parallel_aware)
ExecIndexOnlyScanInitializeDSM((IndexOnlyScanState *) planstate,
d->pcxt);
break;
case T_ForeignScanState:
if (planstate->plan->parallel_aware)
ExecForeignScanInitializeDSM((ForeignScanState *) planstate,
d->pcxt);
break;
case T_AppendState:
if (planstate->plan->parallel_aware)
ExecAppendInitializeDSM((AppendState *) planstate,
d->pcxt);
break;
case T_CustomScanState:
if (planstate->plan->parallel_aware)
ExecCustomScanInitializeDSM((CustomScanState *) planstate,
d->pcxt);
break;
case T_BitmapHeapScanState:
/* GPDB_12_MERGE_FEATURE_NOT_SUPPORTED: the parallel StreamBitmap scan is not implemented */
/*
* if (planstate->plan->parallel_aware)
* ExecBitmapHeapInitializeDSM((BitmapHeapScanState *) planstate,
* d->pcxt);
*/
break;
case T_HashJoinState:
if (planstate->plan->parallel_aware)
ExecHashJoinInitializeDSM((HashJoinState *) planstate,
d->pcxt);
break;
case T_HashState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecHashInitializeDSM((HashState *) planstate, d->pcxt);
break;
case T_SortState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeDSM((SortState *) planstate, d->pcxt);
break;
default:
break;
}
return planstate_tree_walker(planstate, ExecParallelInitializeDSM, d);
}
/*
* It sets up the response queues for backend workers to return tuples
* to the main backend and start the workers.
*/
static shm_mq_handle **
ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
{
shm_mq_handle **responseq;
char *tqueuespace;
int i;
/* Skip this if no workers. */
if (pcxt->nworkers == 0)
return NULL;
/* Allocate memory for shared memory queue handles. */
responseq = (shm_mq_handle **)
palloc(pcxt->nworkers * sizeof(shm_mq_handle *));
/*
* If not reinitializing, allocate space from the DSM for the queues;
* otherwise, find the already allocated space.
*/
if (!reinitialize)
tqueuespace =
shm_toc_allocate(pcxt->toc,
mul_size(PARALLEL_TUPLE_QUEUE_SIZE,
pcxt->nworkers));
else
tqueuespace = shm_toc_lookup(pcxt->toc, PARALLEL_KEY_TUPLE_QUEUE, false);
/* Create the queues, and become the receiver for each. */
for (i = 0; i < pcxt->nworkers; ++i)
{
shm_mq *mq;
mq = shm_mq_create(tqueuespace +
((Size) i) * PARALLEL_TUPLE_QUEUE_SIZE,
(Size) PARALLEL_TUPLE_QUEUE_SIZE);
shm_mq_set_receiver(mq, MyProc);
responseq[i] = shm_mq_attach(mq, pcxt->seg, NULL);
}
/* Add array of queues to shm_toc, so others can find it. */
if (!reinitialize)
shm_toc_insert(pcxt->toc, PARALLEL_KEY_TUPLE_QUEUE, tqueuespace);
/* Return array of handles. */
return responseq;
}
/*
* Sets up the required infrastructure for backend workers to perform
* execution and return results to the main backend.
*/
ParallelExecutorInfo *
ExecInitParallelPlan(PlanState *planstate, EState *estate,
Bitmapset *sendParams, int nworkers,
int64 tuples_needed)
{
ParallelExecutorInfo *pei;
ParallelContext *pcxt;
ExecParallelEstimateContext e;
ExecParallelInitializeDSMContext d;
FixedParallelExecutorState *fpes;
char *pstmt_data;
char *pstmt_space;
char *paramlistinfo_space;
BufferUsage *bufusage_space;
SharedExecutorInstrumentation *instrumentation = NULL;
SharedJitInstrumentation *jit_instrumentation = NULL;
int pstmt_len;
int paramlistinfo_len;
int instrumentation_len = 0;
int jit_instrumentation_len = 0;
int instrument_offset = 0;
Size dsa_minsize = dsa_minimum_size();
char *query_string;
int query_len;
/*
* Force any initplan outputs that we're going to pass to workers to be
* evaluated, if they weren't already.
*
* For simplicity, we use the EState's per-output-tuple ExprContext here.
* That risks intra-query memory leakage, since we might pass through here
* many times before that ExprContext gets reset; but ExecSetParamPlan
* doesn't normally leak any memory in the context (see its comments), so
* it doesn't seem worth complicating this function's API to pass it a
* shorter-lived ExprContext. This might need to change someday.
*/
ExecSetParamPlanMulti(sendParams, GetPerTupleExprContext(estate), NULL);
/* Allocate object for return value. */
pei = palloc0(sizeof(ParallelExecutorInfo));
pei->finished = false;
pei->planstate = planstate;
/* Fix up and serialize plan to be sent to workers. */
pstmt_data = ExecSerializePlan(planstate->plan, estate);
/* Create a parallel context. */
pcxt = CreateParallelContext("postgres", "ParallelQueryMain", nworkers);
pei->pcxt = pcxt;
/*
* Before telling the parallel context to create a dynamic shared memory
* segment, we need to figure out how big it should be. Estimate space
* for the various things we need to store.
*/
/* Estimate space for fixed-size state. */
shm_toc_estimate_chunk(&pcxt->estimator,
sizeof(FixedParallelExecutorState));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for query text. */
query_len = strlen(estate->es_sourceText);
shm_toc_estimate_chunk(&pcxt->estimator, query_len + 1);
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for serialized PlannedStmt. */
pstmt_len = strlen(pstmt_data) + 1;
shm_toc_estimate_chunk(&pcxt->estimator, pstmt_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for serialized ParamListInfo. */
paramlistinfo_len = EstimateParamListSpace(estate->es_param_list_info);
shm_toc_estimate_chunk(&pcxt->estimator, paramlistinfo_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
/*
* Estimate space for BufferUsage.
*
* If EXPLAIN is not in use and there are no extensions loaded that care,
* we could skip this. But we have no way of knowing whether anyone's
* looking at pgBufferUsage, so do it unconditionally.
*/
shm_toc_estimate_chunk(&pcxt->estimator,
mul_size(sizeof(BufferUsage), pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for tuple queues. */
shm_toc_estimate_chunk(&pcxt->estimator,
mul_size(PARALLEL_TUPLE_QUEUE_SIZE, pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/*
* Give parallel-aware nodes a chance to add to the estimates, and get a
* count of how many PlanState nodes there are.
*/
e.pcxt = pcxt;
e.nnodes = 0;
ExecParallelEstimate(planstate, &e);
/* Estimate space for instrumentation, if required. */
if (estate->es_instrument)
{
instrumentation_len =
offsetof(SharedExecutorInstrumentation, plan_node_id) +
sizeof(int) * e.nnodes;
instrumentation_len = MAXALIGN(instrumentation_len);
instrument_offset = instrumentation_len;
instrumentation_len +=
mul_size(sizeof(Instrumentation),
mul_size(e.nnodes, nworkers));
shm_toc_estimate_chunk(&pcxt->estimator, instrumentation_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for JIT instrumentation, if required. */
if (estate->es_jit_flags != PGJIT_NONE)
{
jit_instrumentation_len =
offsetof(SharedJitInstrumentation, jit_instr) +
sizeof(JitInstrumentation) * nworkers;
shm_toc_estimate_chunk(&pcxt->estimator, jit_instrumentation_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
}
/* Estimate space for DSA area. */
shm_toc_estimate_chunk(&pcxt->estimator, dsa_minsize);
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Everyone's had a chance to ask for space, so now create the DSM. */
InitializeParallelDSM(pcxt);
/*
* OK, now we have a dynamic shared memory segment, and it should be big
* enough to store all of the data we estimated we would want to put into
* it, plus whatever general stuff (not specifically executor-related) the
* ParallelContext itself needs to store there. None of the space we
* asked for has been allocated or initialized yet, though, so do that.
*/
/* Store fixed-size state. */
fpes = shm_toc_allocate(pcxt->toc, sizeof(FixedParallelExecutorState));
fpes->tuples_needed = tuples_needed;
fpes->param_exec = InvalidDsaPointer;
fpes->eflags = estate->es_top_eflags;
fpes->jit_flags = estate->es_jit_flags;
shm_toc_insert(pcxt->toc, PARALLEL_KEY_EXECUTOR_FIXED, fpes);
/* Store query string */
query_string = shm_toc_allocate(pcxt->toc, query_len + 1);
memcpy(query_string, estate->es_sourceText, query_len + 1);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_QUERY_TEXT, query_string);
/* Store serialized PlannedStmt. */
pstmt_space = shm_toc_allocate(pcxt->toc, pstmt_len);
memcpy(pstmt_space, pstmt_data, pstmt_len);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_PLANNEDSTMT, pstmt_space);
/* Store serialized ParamListInfo. */
paramlistinfo_space = shm_toc_allocate(pcxt->toc, paramlistinfo_len);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_PARAMLISTINFO, paramlistinfo_space);
SerializeParamList(estate->es_param_list_info, ¶mlistinfo_space);
/* Allocate space for each worker's BufferUsage; no need to initialize. */
bufusage_space = shm_toc_allocate(pcxt->toc,
mul_size(sizeof(BufferUsage), pcxt->nworkers));
shm_toc_insert(pcxt->toc, PARALLEL_KEY_BUFFER_USAGE, bufusage_space);
pei->buffer_usage = bufusage_space;
/* Set up the tuple queues that the workers will write into. */
pei->tqueue = ExecParallelSetupTupleQueues(pcxt, false);
/* We don't need the TupleQueueReaders yet, though. */
pei->reader = NULL;
/*
* If instrumentation options were supplied, allocate space for the data.
* It only gets partially initialized here; the rest happens during
* ExecParallelInitializeDSM.
*/
if (estate->es_instrument)
{
Instrumentation *instrument;
int i;
instrumentation = shm_toc_allocate(pcxt->toc, instrumentation_len);
instrumentation->instrument_options = estate->es_instrument;
instrumentation->instrument_offset = instrument_offset;
instrumentation->num_workers = nworkers;
instrumentation->num_plan_nodes = e.nnodes;
instrument = GetInstrumentationArray(instrumentation);
for (i = 0; i < nworkers * e.nnodes; ++i)
InstrInit(&instrument[i], estate->es_instrument);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_INSTRUMENTATION,
instrumentation);
pei->instrumentation = instrumentation;
if (estate->es_jit_flags != PGJIT_NONE)
{
jit_instrumentation = shm_toc_allocate(pcxt->toc,
jit_instrumentation_len);
jit_instrumentation->num_workers = nworkers;
memset(jit_instrumentation->jit_instr, 0,
sizeof(JitInstrumentation) * nworkers);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_JIT_INSTRUMENTATION,
jit_instrumentation);
pei->jit_instrumentation = jit_instrumentation;
}
}
/*
* Create a DSA area that can be used by the leader and all workers.
* (However, if we failed to create a DSM and are using private memory
* instead, then skip this.)
*/
if (pcxt->seg != NULL)
{
char *area_space;
area_space = shm_toc_allocate(pcxt->toc, dsa_minsize);
shm_toc_insert(pcxt->toc, PARALLEL_KEY_DSA, area_space);
pei->area = dsa_create_in_place(area_space, dsa_minsize,
LWTRANCHE_PARALLEL_QUERY_DSA,
pcxt->seg);
/*
* Serialize parameters, if any, using DSA storage. We don't dare use
* the main parallel query DSM for this because we might relaunch
* workers after the values have changed (and thus the amount of
* storage required has changed).
*/
if (!bms_is_empty(sendParams))
{
pei->param_exec = SerializeParamExecParams(estate, sendParams,
pei->area);
fpes->param_exec = pei->param_exec;
}
}
/*
* Give parallel-aware nodes a chance to initialize their shared data.
* This also initializes the elements of instrumentation->ps_instrument,
* if it exists.
*/
d.pcxt = pcxt;
d.instrumentation = instrumentation;
d.nnodes = 0;
/* Install our DSA area while initializing the plan. */
estate->es_query_dsa = pei->area;
ExecParallelInitializeDSM(planstate, &d);
estate->es_query_dsa = NULL;
/*
* 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)
elog(ERROR, "inconsistent count of PlanState nodes");
/* OK, we're ready to rock and roll. */
return pei;
}
/*
* Set up tuple queue readers to read the results of a parallel subplan.
*
* This is separate from ExecInitParallelPlan() because we can launch the
* worker processes and let them start doing something before we do this.
*/
void
ExecParallelCreateReaders(ParallelExecutorInfo *pei)
{
int nworkers = pei->pcxt->nworkers_launched;
int i;
Assert(pei->reader == NULL);
if (nworkers > 0)
{
pei->reader = (TupleQueueReader **)
palloc(nworkers * sizeof(TupleQueueReader *));
for (i = 0; i < nworkers; i++)
{
shm_mq_set_handle(pei->tqueue[i],
pei->pcxt->worker[i].bgwhandle);
pei->reader[i] = CreateTupleQueueReader(pei->tqueue[i]);
}
}
}
/*
* Re-initialize the parallel executor shared memory state before launching
* a fresh batch of workers.
*/
void
ExecParallelReinitialize(PlanState *planstate,
ParallelExecutorInfo *pei,
Bitmapset *sendParams)
{
EState *estate = planstate->state;
FixedParallelExecutorState *fpes;
/* Old workers must already be shut down */
Assert(pei->finished);
/*
* Force any initplan outputs that we're going to pass to workers to be
* evaluated, if they weren't already (see comments in
* ExecInitParallelPlan).
*/
ExecSetParamPlanMulti(sendParams, GetPerTupleExprContext(estate), NULL);
ReinitializeParallelDSM(pei->pcxt);
pei->tqueue = ExecParallelSetupTupleQueues(pei->pcxt, true);
pei->reader = NULL;
pei->finished = false;
fpes = shm_toc_lookup(pei->pcxt->toc, PARALLEL_KEY_EXECUTOR_FIXED, false);
/* Free any serialized parameters from the last round. */
if (DsaPointerIsValid(fpes->param_exec))
{
dsa_free(pei->area, fpes->param_exec);
fpes->param_exec = InvalidDsaPointer;
}
/* Serialize current parameter values if required. */
if (!bms_is_empty(sendParams))
{
pei->param_exec = SerializeParamExecParams(estate, sendParams,
pei->area);
fpes->param_exec = pei->param_exec;
}
/* Traverse plan tree and let each child node reset associated state. */
estate->es_query_dsa = pei->area;
ExecParallelReInitializeDSM(planstate, pei->pcxt);
estate->es_query_dsa = NULL;
}
/*
* 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.
*/
switch (nodeTag(planstate))
{
case T_SeqScanState:
if (planstate->plan->parallel_aware)
ExecSeqScanReInitializeDSM((SeqScanState *) planstate,
pcxt);
break;
case T_IndexScanState:
if (planstate->plan->parallel_aware)
ExecIndexScanReInitializeDSM((IndexScanState *) planstate,
pcxt);
break;
case T_IndexOnlyScanState:
if (planstate->plan->parallel_aware)
ExecIndexOnlyScanReInitializeDSM((IndexOnlyScanState *) planstate,
pcxt);
break;
case T_ForeignScanState:
if (planstate->plan->parallel_aware)
ExecForeignScanReInitializeDSM((ForeignScanState *) planstate,
pcxt);
break;
case T_AppendState:
if (planstate->plan->parallel_aware)
ExecAppendReInitializeDSM((AppendState *) planstate, pcxt);
break;
case T_CustomScanState:
if (planstate->plan->parallel_aware)
ExecCustomScanReInitializeDSM((CustomScanState *) planstate,
pcxt);
break;
case T_BitmapHeapScanState:
if (planstate->plan->parallel_aware)
ExecBitmapHeapReInitializeDSM((BitmapHeapScanState *) planstate,
pcxt);
break;
case T_HashJoinState:
if (planstate->plan->parallel_aware)
ExecHashJoinReInitializeDSM((HashJoinState *) planstate,
pcxt);
break;
case T_HashState:
case T_SortState:
/* these nodes have DSM state, but no reinitialization is required */
break;
default:
break;
}
return planstate_tree_walker(planstate, ExecParallelReInitializeDSM, pcxt);
}
/*
* Copy instrumentation information about this node and its descendants from
* dynamic shared memory.
*/
static bool
ExecParallelRetrieveInstrumentation(PlanState *planstate,
SharedExecutorInstrumentation *instrumentation)
{
Instrumentation *instrument;
int i;
int n;
int ibytes;
int plan_node_id = planstate->plan->plan_node_id;
MemoryContext oldcontext;
/* Find the instrumentation for this node. */
for (i = 0; i < instrumentation->num_plan_nodes; ++i)
if (instrumentation->plan_node_id[i] == plan_node_id)
break;
if (i >= instrumentation->num_plan_nodes)
elog(ERROR, "plan node %d not found", plan_node_id);
/* Accumulate the statistics from all workers. */
instrument = GetInstrumentationArray(instrumentation);
instrument += i * instrumentation->num_workers;
for (n = 0; n < instrumentation->num_workers; ++n)
InstrAggNode(planstate->instrument, &instrument[n]);
/*
* Also store the per-worker detail.
*
* Worker instrumentation should be allocated in the same context as the
* regular instrumentation information, which is the per-query context.
* Switch into per-query memory context.
*/
oldcontext = MemoryContextSwitchTo(planstate->state->es_query_cxt);
ibytes = mul_size(instrumentation->num_workers, sizeof(Instrumentation));
planstate->worker_instrument =
palloc(ibytes + offsetof(WorkerInstrumentation, instrument));
MemoryContextSwitchTo(oldcontext);
planstate->worker_instrument->num_workers = instrumentation->num_workers;
memcpy(&planstate->worker_instrument->instrument, instrument, ibytes);
/* Perform any node-type-specific work that needs to be done. */
switch (nodeTag(planstate))
{
case T_SortState:
ExecSortRetrieveInstrumentation((SortState *) planstate);
break;
case T_HashState:
ExecHashRetrieveInstrumentation((HashState *) planstate);
break;
default:
break;
}
return planstate_tree_walker(planstate, ExecParallelRetrieveInstrumentation,
instrumentation);
}
/*
* Add up the workers' JIT instrumentation from dynamic shared memory.
*/
static void
ExecParallelRetrieveJitInstrumentation(PlanState *planstate,
SharedJitInstrumentation *shared_jit)
{
JitInstrumentation *combined;
int ibytes;
int n;
/*
* Accumulate worker JIT instrumentation into the combined JIT
* instrumentation, allocating it if required.
*/
if (!planstate->state->es_jit_worker_instr)
planstate->state->es_jit_worker_instr =
MemoryContextAllocZero(planstate->state->es_query_cxt, sizeof(JitInstrumentation));
combined = planstate->state->es_jit_worker_instr;
/* Accumulate all the workers' instrumentations. */
for (n = 0; n < shared_jit->num_workers; ++n)
InstrJitAgg(combined, &shared_jit->jit_instr[n]);
/*
* Store the per-worker detail.
*
* Similar to ExecParallelRetrieveInstrumentation(), allocate the
* instrumentation in per-query context.
*/
ibytes = offsetof(SharedJitInstrumentation, jit_instr)
+ mul_size(shared_jit->num_workers, sizeof(JitInstrumentation));
planstate->worker_jit_instrument =
MemoryContextAlloc(planstate->state->es_query_cxt, ibytes);
memcpy(planstate->worker_jit_instrument, shared_jit, ibytes);
}
/*
* Finish parallel execution. We wait for parallel workers to finish, and
* accumulate their buffer usage.
*/
void
ExecParallelFinish(ParallelExecutorInfo *pei)
{
int nworkers = pei->pcxt->nworkers_launched;
int i;
/* Make this be a no-op if called twice in a row. */
if (pei->finished)
return;
/*
* Detach from tuple queues ASAP, so that any still-active workers will
* notice that no further results are wanted.
*/
if (pei->tqueue != NULL)
{
for (i = 0; i < nworkers; i++)
shm_mq_detach(pei->tqueue[i]);
pfree(pei->tqueue);
pei->tqueue = NULL;
}
/*
* While we're waiting for the workers to finish, let's get rid of the
* tuple queue readers. (Any other local cleanup could be done here too.)
*/
if (pei->reader != NULL)
{
for (i = 0; i < nworkers; i++)
DestroyTupleQueueReader(pei->reader[i]);
pfree(pei->reader);
pei->reader = NULL;
}
/* Now wait for the workers to finish. */
WaitForParallelWorkersToFinish(pei->pcxt);
/*
* Next, accumulate buffer usage. (This must wait for the workers to
* finish, or we might get incomplete data.)
*/
for (i = 0; i < nworkers; i++)
InstrAccumParallelQuery(&pei->buffer_usage[i]);
pei->finished = true;
}
/*
* 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);
/* Accumulate JIT instrumentation, if any. */
if (pei->jit_instrumentation)
ExecParallelRetrieveJitInstrumentation(pei->planstate,
pei->jit_instrumentation);
/* Free any serialized parameters. */
if (DsaPointerIsValid(pei->param_exec))
{
dsa_free(pei->area, pei->param_exec);
pei->param_exec = InvalidDsaPointer;
}
if (pei->area != NULL)
{
dsa_detach(pei->area);
pei->area = NULL;
}
if (pei->pcxt != NULL)
{
DestroyParallelContext(pei->pcxt);
pei->pcxt = NULL;
}
pfree(pei);
}
/*
* Create a DestReceiver to write tuples we produce to the shm_mq designated
* for that purpose.
*/
static DestReceiver *
ExecParallelGetReceiver(dsm_segment *seg, shm_toc *toc)
{
char *mqspace;
shm_mq *mq;
mqspace = shm_toc_lookup(toc, PARALLEL_KEY_TUPLE_QUEUE, false);
mqspace += ParallelWorkerNumber * PARALLEL_TUPLE_QUEUE_SIZE;
mq = (shm_mq *) mqspace;
shm_mq_set_sender(mq, MyProc);
return CreateTupleQueueDestReceiver(shm_mq_attach(mq, seg, NULL));
}
/*
* Create a QueryDesc for the PlannedStmt we are to execute, and return it.
*/
static QueryDesc *
ExecParallelGetQueryDesc(shm_toc *toc, DestReceiver *receiver,
int instrument_options)
{
char *pstmtspace;
char *paramspace;
PlannedStmt *pstmt;
ParamListInfo paramLI;
char *queryString;
/* Get the query string from shared memory */
queryString = shm_toc_lookup(toc, PARALLEL_KEY_QUERY_TEXT, false);
/* Reconstruct leader-supplied PlannedStmt. */
pstmtspace = shm_toc_lookup(toc, PARALLEL_KEY_PLANNEDSTMT, false);
pstmt = (PlannedStmt *) stringToNode(pstmtspace);
/* Reconstruct ParamListInfo. */
paramspace = shm_toc_lookup(toc, PARALLEL_KEY_PARAMLISTINFO, false);
paramLI = RestoreParamList(¶mspace);
/* Create a QueryDesc for the query. */
return CreateQueryDesc(pstmt,
queryString,
GetActiveSnapshot(), InvalidSnapshot,
receiver, paramLI, NULL, instrument_options);
}
/*
* Copy instrumentation information from this node and its descendants into
* dynamic shared memory, so that the parallel leader can retrieve it.
*/
static bool
ExecParallelReportInstrumentation(PlanState *planstate,
SharedExecutorInstrumentation *instrumentation)
{
int i;
int plan_node_id = planstate->plan->plan_node_id;
Instrumentation *instrument;
InstrEndLoop(planstate->instrument);
/*
* If we shuffled the plan_node_id values in ps_instrument into sorted
* order, we could use binary search here. This might matter someday if
* we're pushing down sufficiently large plan trees. For now, do it the
* slow, dumb way.
*/
for (i = 0; i < instrumentation->num_plan_nodes; ++i)
if (instrumentation->plan_node_id[i] == plan_node_id)
break;
if (i >= instrumentation->num_plan_nodes)
elog(ERROR, "plan node %d not found", plan_node_id);
/*
* Add our statistics to the per-node, per-worker totals. It's possible
* that this could happen more than once if we relaunched workers.
*/
instrument = GetInstrumentationArray(instrumentation);
instrument += i * instrumentation->num_workers;
Assert(IsParallelWorker());
Assert(ParallelWorkerNumber < instrumentation->num_workers);
InstrAggNode(&instrument[ParallelWorkerNumber], planstate->instrument);
return planstate_tree_walker(planstate, ExecParallelReportInstrumentation,
instrumentation);
}
/*
* Initialize the PlanState and its descendants with the information
* retrieved from shared memory. This has to be done once the PlanState
* is allocated and initialized by executor; that is, after ExecutorStart().
*/
static bool
ExecParallelInitializeWorker(PlanState *planstate, ParallelWorkerContext *pwcxt)
{
if (planstate == NULL)
return false;
switch (nodeTag(planstate))
{
case T_SeqScanState:
if (planstate->plan->parallel_aware)
ExecSeqScanInitializeWorker((SeqScanState *) planstate, pwcxt);
break;
case T_IndexScanState:
if (planstate->plan->parallel_aware)
ExecIndexScanInitializeWorker((IndexScanState *) planstate,
pwcxt);
break;
case T_IndexOnlyScanState:
if (planstate->plan->parallel_aware)
ExecIndexOnlyScanInitializeWorker((IndexOnlyScanState *) planstate,
pwcxt);
break;
case T_ForeignScanState:
if (planstate->plan->parallel_aware)
ExecForeignScanInitializeWorker((ForeignScanState *) planstate,
pwcxt);
break;
case T_AppendState:
if (planstate->plan->parallel_aware)
ExecAppendInitializeWorker((AppendState *) planstate, pwcxt);
break;
case T_CustomScanState:
if (planstate->plan->parallel_aware)
ExecCustomScanInitializeWorker((CustomScanState *) planstate,
pwcxt);
break;
case T_BitmapHeapScanState:
if (planstate->plan->parallel_aware)
ExecBitmapHeapInitializeWorker((BitmapHeapScanState *) planstate,
pwcxt);
break;
case T_HashJoinState:
if (planstate->plan->parallel_aware)
ExecHashJoinInitializeWorker((HashJoinState *) planstate,
pwcxt);
break;
case T_HashState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecHashInitializeWorker((HashState *) planstate, pwcxt);
break;
case T_SortState:
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeWorker((SortState *) planstate, pwcxt);
break;
default:
break;
}
return planstate_tree_walker(planstate, ExecParallelInitializeWorker,
pwcxt);
}
/*
* Main entrypoint for parallel query worker processes.
*
* We reach this function from ParallelWorkerMain, so the setup necessary to
* create a sensible parallel environment has already been done;
* ParallelWorkerMain worries about stuff like the transaction state, combo
* CID mappings, and GUC values, so we don't need to deal with any of that
* here.
*
* Our job is to deal with concerns specific to the executor. The parallel
* group leader will have stored a serialized PlannedStmt, and it's our job
* to execute that plan and write the resulting tuples to the appropriate
* tuple queue. Various bits of supporting information that we need in order
* to do this are also stored in the dsm_segment and can be accessed through
* the shm_toc.
*/
void
ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
{
FixedParallelExecutorState *fpes;
BufferUsage *buffer_usage;
DestReceiver *receiver;
QueryDesc *queryDesc;
SharedExecutorInstrumentation *instrumentation;
SharedJitInstrumentation *jit_instrumentation;
int instrument_options = 0;
void *area_space;
dsa_area *area;
ParallelWorkerContext pwcxt;
/* Get fixed-size state. */
fpes = shm_toc_lookup(toc, PARALLEL_KEY_EXECUTOR_FIXED, false);
/* Set up DestReceiver, SharedExecutorInstrumentation, and QueryDesc. */
receiver = ExecParallelGetReceiver(seg, toc);
instrumentation = shm_toc_lookup(toc, PARALLEL_KEY_INSTRUMENTATION, true);
if (instrumentation != NULL)
instrument_options = instrumentation->instrument_options;
jit_instrumentation = shm_toc_lookup(toc, PARALLEL_KEY_JIT_INSTRUMENTATION,
true);
queryDesc = ExecParallelGetQueryDesc(toc, receiver, instrument_options);
/* Setting debug_query_string for individual workers */
debug_query_string = queryDesc->sourceText;
/* Report workers' query for monitoring purposes */
pgstat_report_activity(STATE_RUNNING, debug_query_string);
/* Attach to the dynamic shared memory area. */
area_space = shm_toc_lookup(toc, PARALLEL_KEY_DSA, false);
area = dsa_attach_in_place(area_space, seg);
/* Start up the executor */
queryDesc->plannedstmt->jitFlags = fpes->jit_flags;
ExecutorStart(queryDesc, fpes->eflags);
/* Special executor initialization steps for parallel workers */
queryDesc->planstate->state->es_query_dsa = area;
if (DsaPointerIsValid(fpes->param_exec))
{
char *paramexec_space;
paramexec_space = dsa_get_address(area, fpes->param_exec);
RestoreParamExecParams(paramexec_space, queryDesc->estate);
}
pwcxt.toc = toc;
pwcxt.seg = seg;
ExecParallelInitializeWorker(queryDesc->planstate, &pwcxt);
/* Pass down any tuple bound */
ExecSetTupleBound(fpes->tuples_needed, queryDesc->planstate);
/*
* Prepare to track buffer usage during query execution.
*
* We do this after starting up the executor to match what happens in the
* leader, which also doesn't count buffer accesses that occur during
* executor startup.
*/
InstrStartParallelQuery();
/*
* Run the plan. If we specified a tuple bound, be careful not to demand
* more tuples than that.
*/
ExecutorRun(queryDesc,
ForwardScanDirection,
fpes->tuples_needed < 0 ? (int64) 0 : fpes->tuples_needed,
true);
/* Shut down the executor */
ExecutorFinish(queryDesc);
/* Report buffer usage during parallel execution. */
buffer_usage = shm_toc_lookup(toc, PARALLEL_KEY_BUFFER_USAGE, false);
InstrEndParallelQuery(&buffer_usage[ParallelWorkerNumber]);
/* Report instrumentation data if any instrumentation options are set. */
if (instrumentation != NULL)
ExecParallelReportInstrumentation(queryDesc->planstate,
instrumentation);
/* Report JIT instrumentation data if any */
if (queryDesc->estate->es_jit && jit_instrumentation != NULL)
{
Assert(ParallelWorkerNumber < jit_instrumentation->num_workers);
jit_instrumentation->jit_instr[ParallelWorkerNumber] =
queryDesc->estate->es_jit->instr;
}
/* Must do this after capturing instrumentation. */
ExecutorEnd(queryDesc);
/* Cleanup. */
dsa_detach(area);
FreeQueryDesc(queryDesc);
receiver->rDestroy(receiver);
}
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