v9-0002-Implements-logging-for-parallel-worker-usage-in-util.patch

From 7184271007622c7fe2f1e3c09506a38e4e874187 Mon Sep 17 00:00:00 2001
From: benoit <benoit.lobreau@dalibo.com>
Date: Wed, 29 Jan 2025 17:10:57 +0100
Subject: [PATCH 2/3] Implements logging for parallel worker usage in utilities

This patch implements logging of parallel worker usage for:
* the index cleanup and bulkdelete phases of vacuum;
* btree, brin and gin index builds.
---
 src/backend/access/brin/brin.c        |  4 ++++
 src/backend/access/gin/gininsert.c    |  4 ++++
 src/backend/access/nbtree/nbtsort.c   |  4 ++++
 src/backend/commands/vacuumparallel.c | 13 +++++++++++++
 4 files changed, 25 insertions(+)

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 01e1db7f856..b69caeed0ad 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -2552,6 +2552,10 @@ _brin_end_parallel(BrinLeader *brinleader, BrinBuildState *state)
 	/* Shutdown worker processes */
 	WaitForParallelWorkersToFinish(brinleader->pcxt);
 
+	LogParallelWorkersIfNeeded(log_parallel_workers,
+							   brinleader->pcxt->nworkers_to_launch,
+							   brinleader->pcxt->nworkers_launched);
+
 	/*
 	 * Next, accumulate WAL usage.  (This must wait for the workers to finish,
 	 * or we might get incomplete data.)
diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index cfab93ec30c..c2a7ab0b177 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -1079,6 +1079,10 @@ _gin_end_parallel(GinLeader *ginleader, GinBuildState *state)
 	/* Shutdown worker processes */
 	WaitForParallelWorkersToFinish(ginleader->pcxt);
 
+	LogParallelWorkersIfNeeded(log_parallel_workers,
+							   ginleader->pcxt->nworkers_to_launch,
+							   ginleader->pcxt->nworkers_launched);
+
 	/*
 	 * Next, accumulate WAL usage.  (This must wait for the workers to finish,
 	 * or we might get incomplete data.)
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index 3794cc924ad..e48deed9035 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -1613,6 +1613,10 @@ _bt_end_parallel(BTLeader *btleader)
 	/* Shutdown worker processes */
 	WaitForParallelWorkersToFinish(btleader->pcxt);
 
+	LogParallelWorkersIfNeeded(log_parallel_workers,
+							   btleader->pcxt->nworkers_to_launch,
+							   btleader->pcxt->nworkers_launched);
+
 	/*
 	 * Next, accumulate WAL usage.  (This must wait for the workers to finish,
 	 * or we might get incomplete data.)
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index 2b9d548cdeb..01dee17741a 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -208,6 +208,9 @@ struct ParallelVacuumState
 	int			nindexes_parallel_cleanup;
 	int			nindexes_parallel_condcleanup;
 
+	int			nworkers_to_launch;
+	int			nworkers_launched;
+
 	/* Buffer access strategy used by leader process */
 	BufferAccessStrategy bstrategy;
 
@@ -362,6 +365,9 @@ parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,
 		if ((vacoptions & VACUUM_OPTION_PARALLEL_COND_CLEANUP) != 0)
 			pvs->nindexes_parallel_condcleanup++;
 	}
+	pvs->nworkers_to_launch = 0;
+	pvs->nworkers_launched = 0;
+
 	shm_toc_insert(pcxt->toc, PARALLEL_VACUUM_KEY_INDEX_STATS, indstats);
 	pvs->indstats = indstats;
 
@@ -437,6 +443,10 @@ parallel_vacuum_end(ParallelVacuumState *pvs, IndexBulkDeleteResult **istats)
 {
 	Assert(!IsParallelWorker());
 
+	LogParallelWorkersIfNeeded(log_parallel_workers,
+							   pvs->nworkers_to_launch,
+							   pvs->nworkers_launched);
+
 	/* Copy the updated statistics */
 	for (int i = 0; i < pvs->nindexes; i++)
 	{
@@ -738,6 +748,9 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
 
 		for (int i = 0; i < pvs->pcxt->nworkers_launched; i++)
 			InstrAccumParallelQuery(&pvs->buffer_usage[i], &pvs->wal_usage[i]);
+
+		pvs->nworkers_to_launch += pvs->pcxt->nworkers_to_launch;
+		pvs->nworkers_launched += pvs->pcxt->nworkers_launched;
 	}
 
 	/*
-- 
2.48.1