Collect JIT instrumentation from workers.

Previously, when using parallel query, EXPLAIN (ANALYZE)'s JIT
compilation timings did not include the overhead from doing so on the
workers.  Fix that.

We do so by simply aggregating the cost of doing JIT compilation on
workers and the leader together. Arguably that's not quite accurate,
because the total time spend doing so is spent in parallel - but it's
hard to do much better.  For additional detail, when VERBOSE is
specified, the stats for workers are displayed separately.

Author: Amit Khandekar and Andres Freund
Discussion: https://postgr.es/m/CAJ3gD9eLrz51RK_gTkod+71iDcjpB_N8eC6vU2AW-VicsAERpQ@mail.gmail.com
Backpatch: 11-

Author: anarazel

contrib/auto_explain/auto_explain.c

@@ -362,9 +362,9 @@ explain_ExecutorEnd(QueryDesc *queryDesc)
 			ExplainPrintPlan(es, queryDesc);
 			if (es->analyze && auto_explain_log_triggers)
 				ExplainPrintTriggers(es, queryDesc);
-			if (queryDesc->estate->es_jit && es->costs &&
-				queryDesc->estate->es_jit->created_functions > 0)
-				ExplainPrintJIT(es, queryDesc);
+			if (es->costs)
+				ExplainPrintJIT(es, queryDesc->estate->es_jit_flags,
+								queryDesc->estate->es_jit_combined_instr, -1);
 			ExplainEndOutput(es);
 
 			/* Remove last line break */

src/backend/commands/explain.c

@@ -563,9 +563,9 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 	 * depending on build options.  Might want to separate that out from COSTS
 	 * at a later stage.
 	 */
-	if (queryDesc->estate->es_jit && es->costs &&
-		queryDesc->estate->es_jit->created_functions > 0)
-		ExplainPrintJIT(es, queryDesc);
+	if (es->costs)
+		ExplainPrintJIT(es, queryDesc->estate->es_jit_flags,
+						queryDesc->estate->es_jit_combined_instr, -1);
 
 	/*
 	 * Close down the query and free resources.  Include time for this in the
@@ -691,78 +691,90 @@ ExplainPrintTriggers(ExplainState *es, QueryDesc *queryDesc)
 /*
  * ExplainPrintJIT -
  *	  Append information about JITing to es->str.
+ *
+ * Can be used to print the JIT instrumentation of the backend (worker_num =
+ * -1) or that of a specific worker (worker_num = ...).
  */
 void
-ExplainPrintJIT(ExplainState *es, QueryDesc *queryDesc)
+ExplainPrintJIT(ExplainState *es, int jit_flags,
+				JitInstrumentation *ji, int worker_num)
 {
-	JitContext *jc = queryDesc->estate->es_jit;
 	instr_time	total_time;
+	bool		for_workers = (worker_num >= 0);
+
+	/* don't print information if no JITing happened */
+	if (!ji || ji->created_functions == 0)
+		return;
 
 	/* calculate total time */
 	INSTR_TIME_SET_ZERO(total_time);
-	INSTR_TIME_ADD(total_time, jc->generation_counter);
-	INSTR_TIME_ADD(total_time, jc->inlining_counter);
-	INSTR_TIME_ADD(total_time, jc->optimization_counter);
-	INSTR_TIME_ADD(total_time, jc->emission_counter);
+	INSTR_TIME_ADD(total_time, ji->generation_counter);
+	INSTR_TIME_ADD(total_time, ji->inlining_counter);
+	INSTR_TIME_ADD(total_time, ji->optimization_counter);
+	INSTR_TIME_ADD(total_time, ji->emission_counter);
 
 	ExplainOpenGroup("JIT", "JIT", true, es);
 
 	/* for higher density, open code the text output format */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 	{
 		appendStringInfoSpaces(es->str, es->indent * 2);
-		appendStringInfo(es->str, "JIT:\n");
+		if (for_workers)
+			appendStringInfo(es->str, "JIT for worker %u:\n", worker_num);
+		else
+			appendStringInfo(es->str, "JIT:\n");
 		es->indent += 1;
 
-		ExplainPropertyInteger("Functions", NULL, jc->created_functions, es);
+		ExplainPropertyInteger("Functions", NULL, ji->created_functions, es);
 
 		appendStringInfoSpaces(es->str, es->indent * 2);
 		appendStringInfo(es->str, "Options: %s %s, %s %s, %s %s, %s %s\n",
-						 "Inlining", jc->flags & PGJIT_INLINE ? "true" : "false",
-						 "Optimization", jc->flags & PGJIT_OPT3 ? "true" : "false",
-						 "Expressions", jc->flags & PGJIT_EXPR ? "true" : "false",
-						 "Deforming", jc->flags & PGJIT_DEFORM ? "true" : "false");
+						 "Inlining", jit_flags & PGJIT_INLINE ? "true" : "false",
+						 "Optimization", jit_flags & PGJIT_OPT3 ? "true" : "false",
+						 "Expressions", jit_flags & PGJIT_EXPR ? "true" : "false",
+						 "Deforming", jit_flags & PGJIT_DEFORM ? "true" : "false");
 
 		if (es->analyze && es->timing)
 		{
 			appendStringInfoSpaces(es->str, es->indent * 2);
 			appendStringInfo(es->str,
 							 "Timing: %s %.3f ms, %s %.3f ms, %s %.3f ms, %s %.3f ms, %s %.3f ms\n",
-							 "Generation", 1000.0 * INSTR_TIME_GET_DOUBLE(jc->generation_counter),
-							 "Inlining", 1000.0 * INSTR_TIME_GET_DOUBLE(jc->inlining_counter),
-							 "Optimization", 1000.0 * INSTR_TIME_GET_DOUBLE(jc->optimization_counter),
-							 "Emission", 1000.0 * INSTR_TIME_GET_DOUBLE(jc->emission_counter),
+							 "Generation", 1000.0 * INSTR_TIME_GET_DOUBLE(ji->generation_counter),
+							 "Inlining", 1000.0 * INSTR_TIME_GET_DOUBLE(ji->inlining_counter),
+							 "Optimization", 1000.0 * INSTR_TIME_GET_DOUBLE(ji->optimization_counter),
+							 "Emission", 1000.0 * INSTR_TIME_GET_DOUBLE(ji->emission_counter),
 							 "Total", 1000.0 * INSTR_TIME_GET_DOUBLE(total_time));
 		}
 
 		es->indent -= 1;
 	}
 	else
 	{
-		ExplainPropertyInteger("Functions", NULL, jc->created_functions, es);
+		ExplainPropertyInteger("Worker Number", NULL, worker_num, es);
+		ExplainPropertyInteger("Functions", NULL, ji->created_functions, es);
 
 		ExplainOpenGroup("Options", "Options", true, es);
-		ExplainPropertyBool("Inlining", jc->flags & PGJIT_INLINE, es);
-		ExplainPropertyBool("Optimization", jc->flags & PGJIT_OPT3, es);
-		ExplainPropertyBool("Expressions", jc->flags & PGJIT_EXPR, es);
-		ExplainPropertyBool("Deforming", jc->flags & PGJIT_DEFORM, es);
+		ExplainPropertyBool("Inlining", jit_flags & PGJIT_INLINE, es);
+		ExplainPropertyBool("Optimization", jit_flags & PGJIT_OPT3, es);
+		ExplainPropertyBool("Expressions", jit_flags & PGJIT_EXPR, es);
+		ExplainPropertyBool("Deforming", jit_flags & PGJIT_DEFORM, es);
 		ExplainCloseGroup("Options", "Options", true, es);
 
 		if (es->analyze && es->timing)
 		{
 			ExplainOpenGroup("Timing", "Timing", true, es);
 
 			ExplainPropertyFloat("Generation", "ms",
-								 1000.0 * INSTR_TIME_GET_DOUBLE(jc->generation_counter),
+								 1000.0 * INSTR_TIME_GET_DOUBLE(ji->generation_counter),
 								 3, es);
 			ExplainPropertyFloat("Inlining", "ms",
-								 1000.0 * INSTR_TIME_GET_DOUBLE(jc->inlining_counter),
+								 1000.0 * INSTR_TIME_GET_DOUBLE(ji->inlining_counter),
 								 3, es);
 			ExplainPropertyFloat("Optimization", "ms",
-								 1000.0 * INSTR_TIME_GET_DOUBLE(jc->optimization_counter),
+								 1000.0 * INSTR_TIME_GET_DOUBLE(ji->optimization_counter),
 								 3, es);
 			ExplainPropertyFloat("Emission", "ms",
-								 1000.0 * INSTR_TIME_GET_DOUBLE(jc->emission_counter),
+								 1000.0 * INSTR_TIME_GET_DOUBLE(ji->emission_counter),
 								 3, es);
 			ExplainPropertyFloat("Total", "ms",
 								 1000.0 * INSTR_TIME_GET_DOUBLE(total_time),
@@ -1554,6 +1566,25 @@ ExplainNode(PlanState *planstate, List *ancestors,
 					ExplainPropertyInteger("Workers Launched", NULL,
 										   nworkers, es);
 				}
+
+				/*
+				 * Print per-worker Jit instrumentation. Use same conditions
+				 * as for the leader's JIT instrumentation, see comment there.
+				 */
+				if (es->costs && es->verbose &&
+					outerPlanState(planstate)->worker_jit_instrument)
+				{
+					PlanState *child = outerPlanState(planstate);
+					int			n;
+					SharedJitInstrumentation *w = child->worker_jit_instrument;
+
+					for (n = 0; n < w->num_workers; ++n)
+					{
+						ExplainPrintJIT(es, child->state->es_jit_flags,
+										&w->jit_instr[n], n);
+					}
+				}
+
 				if (gather->single_copy || es->format != EXPLAIN_FORMAT_TEXT)
 					ExplainPropertyBool("Single Copy", gather->single_copy, es);
 			}

src/backend/executor/execMain.c

@@ -48,6 +48,7 @@
 #include "executor/execdebug.h"
 #include "executor/nodeSubplan.h"
 #include "foreign/fdwapi.h"
+#include "jit/jit.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "optimizer/clauses.h"
@@ -494,6 +495,21 @@ standard_ExecutorEnd(QueryDesc *queryDesc)
 
 	ExecEndPlan(queryDesc->planstate, estate);
 
+	/*
+	 * If this process has done JIT, either merge stats into worker stats, or
+	 * use this process' stats as the global stats if no parallelism was used
+	 * / no workers did JIT.
+	 */
+	if (estate->es_instrument && queryDesc->estate->es_jit)
+	{
+		if (queryDesc->estate->es_jit_combined_instr)
+			InstrJitAgg(queryDesc->estate->es_jit_combined_instr,
+						&queryDesc->estate->es_jit->instr);
+		else
+			queryDesc->estate->es_jit_combined_instr =
+				&queryDesc->estate->es_jit->instr;
+	}
+
 	/* do away with our snapshots */
 	UnregisterSnapshot(estate->es_snapshot);
 	UnregisterSnapshot(estate->es_crosscheck_snapshot);

src/backend/executor/execParallel.c

@@ -37,6 +37,7 @@
 #include "executor/nodeSort.h"
 #include "executor/nodeSubplan.h"
 #include "executor/tqueue.h"
+#include "jit/jit.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/planmain.h"
 #include "optimizer/planner.h"
@@ -62,6 +63,7 @@
 #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
 
@@ -573,9 +575,11 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
 	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;
@@ -669,6 +673,16 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
 					 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. */
@@ -742,6 +756,18 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
 		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;
+		}
 	}
 
 	/*
@@ -1003,6 +1029,46 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
 								 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. Note this is kept separate
+	 * from the leader's own instrumentation.
+	 */
+	if (!planstate->state->es_jit_combined_instr)
+		planstate->state->es_jit_combined_instr =
+			MemoryContextAllocZero(planstate->state->es_query_cxt, sizeof(JitInstrumentation));
+	combined = planstate->state->es_jit_combined_instr;
+
+	/* Accummulate 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.
@@ -1068,6 +1134,11 @@ ExecParallelCleanup(ParallelExecutorInfo *pei)
 		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))
 	{
@@ -1274,6 +1345,7 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
 	DestReceiver *receiver;
 	QueryDesc  *queryDesc;
 	SharedExecutorInstrumentation *instrumentation;
+	SharedJitInstrumentation *jit_instrumentation;
 	int			instrument_options = 0;
 	void	   *area_space;
 	dsa_area   *area;
@@ -1287,6 +1359,8 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *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 */
@@ -1350,6 +1424,14 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
 		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);
 

src/backend/jit/jit.c

@@ -182,6 +182,17 @@ jit_compile_expr(struct ExprState *state)
 	return false;
 }
 
+/* Aggregate JIT instrumentation information */
+void
+InstrJitAgg(JitInstrumentation *dst, JitInstrumentation *add)
+{
+	dst->created_functions += add->created_functions;
+	INSTR_TIME_ADD(dst->generation_counter, add->generation_counter);
+	INSTR_TIME_ADD(dst->inlining_counter, add->inlining_counter);
+	INSTR_TIME_ADD(dst->optimization_counter, add->optimization_counter);
+	INSTR_TIME_ADD(dst->emission_counter, add->emission_counter);
+}
+
 static bool
 file_exists(const char *name)
 {