v4-0001-Introduce-two-new-counters-in-EState-for-parallel.patch

From 5dc567cda5ad9e0c41532ef6ce5cc5f1808e974e Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Tue, 8 Oct 2024 15:52:38 +0900
Subject: [PATCH v4 1/3] Introduce two new counters in EState for parallel
 workers

They will be used by some follow-up patches to populate other parts of
the system with this data extracted from the executor.
---
 src/include/nodes/execnodes.h          | 5 +++++
 src/backend/executor/execUtils.c       | 2 ++
 src/backend/executor/nodeGather.c      | 7 +++++++
 src/backend/executor/nodeGatherMerge.c | 7 +++++++
 4 files changed, 21 insertions(+)

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index aab59d681c..e4698a28c4 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -708,6 +708,11 @@ typedef struct EState
 
 	bool		es_use_parallel_mode;	/* can we use parallel workers? */
 
+	int			es_parallel_workers_to_launch;	/* number of workers to
+												 * launch. */
+	int			es_parallel_workers_launched;	/* number of workers actually
+												 * launched. */
+
 	/* The per-query shared memory area to use for parallel execution. */
 	struct dsa_area *es_query_dsa;
 
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 5737f9f4eb..6712302ec8 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -158,6 +158,8 @@ CreateExecutorState(void)
 	estate->es_sourceText = NULL;
 
 	estate->es_use_parallel_mode = false;
+	estate->es_parallel_workers_to_launch = 0;
+	estate->es_parallel_workers_launched = 0;
 
 	estate->es_jit_flags = 0;
 	estate->es_jit = NULL;
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c
index 5d4ffe989c..7f7edc7f9f 100644
--- a/src/backend/executor/nodeGather.c
+++ b/src/backend/executor/nodeGather.c
@@ -182,6 +182,13 @@ ExecGather(PlanState *pstate)
 			/* We save # workers launched for the benefit of EXPLAIN */
 			node->nworkers_launched = pcxt->nworkers_launched;
 
+			/*
+			 * Count number of workers originally wanted and actually
+			 * launched.
+			 */
+			estate->es_parallel_workers_to_launch += pcxt->nworkers_to_launch;
+			estate->es_parallel_workers_launched += pcxt->nworkers_launched;
+
 			/* Set up tuple queue readers to read the results. */
 			if (pcxt->nworkers_launched > 0)
 			{
diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c
index 45f6017c29..bc99c0b448 100644
--- a/src/backend/executor/nodeGatherMerge.c
+++ b/src/backend/executor/nodeGatherMerge.c
@@ -223,6 +223,13 @@ ExecGatherMerge(PlanState *pstate)
 			/* We save # workers launched for the benefit of EXPLAIN */
 			node->nworkers_launched = pcxt->nworkers_launched;
 
+			/*
+			 * Count number of workers originally wanted and actually
+			 * launched.
+			 */
+			estate->es_parallel_workers_to_launch += pcxt->nworkers_to_launch;
+			estate->es_parallel_workers_launched += pcxt->nworkers_launched;
+
 			/* Set up tuple queue readers to read the results. */
 			if (pcxt->nworkers_launched > 0)
 			{
-- 
2.45.2