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-

1 files changed, 59 insertions, 28 deletions

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 01520154e48..ed6afe79a9f 100644
--- a/src/backend/commands/explain.c
+++ b/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
@@ -691,19 +691,27 @@ 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);
 
@@ -711,27 +719,30 @@ ExplainPrintJIT(ExplainState *es, QueryDesc *queryDesc)
 	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));
 		}
 
@@ -739,13 +750,14 @@ ExplainPrintJIT(ExplainState *es, QueryDesc *queryDesc)
 	}
 	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)
@@ -753,16 +765,16 @@ ExplainPrintJIT(ExplainState *es, QueryDesc *queryDesc)
 			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);
 			}