v23-0002-Logging-for-parallel-autovacuum.patch

From 4b4fe2edb57dc6d910dc7a37161bede4e752d982 Mon Sep 17 00:00:00 2001
From: Daniil Davidov <d.davydov@postgrespro.ru>
Date: Sun, 23 Nov 2025 01:07:47 +0700
Subject: [PATCH v23 2/5] Logging for parallel autovacuum

---
 src/backend/access/heap/vacuumlazy.c  | 54 ++++++++++++++++++++++++++-
 src/backend/commands/vacuumparallel.c | 32 +++++++++++++---
 src/include/commands/vacuum.h         | 39 ++++++++++++++++++-
 src/tools/pgindent/typedefs.list      |  2 +
 4 files changed, 117 insertions(+), 10 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 5d271d80967..1e2d5be1af2 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -342,6 +342,13 @@ typedef struct LVRelState
 	int			num_index_scans;
 	int			num_dead_items_resets;
 	Size		total_dead_items_bytes;
+
+	/*
+	 * Total number of planned and actually launched parallel workers for
+	 * index scans.
+	 */
+	PVWorkersUsage workers_usage;
+
 	/* Counters that follow are only for scanned_pages */
 	int64		tuples_deleted; /* # deleted from table */
 	int64		tuples_frozen;	/* # newly frozen */
@@ -780,6 +787,11 @@ heap_vacuum_rel(Relation rel, const VacuumParams params,
 	vacrel->new_all_visible_all_frozen_pages = 0;
 	vacrel->new_all_frozen_pages = 0;
 
+	vacrel->workers_usage.vacuum.nlaunched = 0;
+	vacrel->workers_usage.vacuum.nplanned = 0;
+	vacrel->workers_usage.cleanup.nlaunched = 0;
+	vacrel->workers_usage.cleanup.nplanned = 0;
+
 	/*
 	 * Get cutoffs that determine which deleted tuples are considered DEAD,
 	 * not just RECENTLY_DEAD, and which XIDs/MXIDs to freeze.  Then determine
@@ -1122,6 +1134,42 @@ heap_vacuum_rel(Relation rel, const VacuumParams params,
 							 orig_rel_pages == 0 ? 100.0 :
 							 100.0 * vacrel->lpdead_item_pages / orig_rel_pages,
 							 vacrel->lpdead_items);
+			if (vacrel->workers_usage.vacuum.nplanned > 0)
+			{
+				if (AmAutoVacuumWorkerProcess())
+				{
+					appendStringInfo(&buf,
+									 _("parallel workers: index vacuum: %d planned, %d reserved, %d launched in total\n"),
+									 vacrel->workers_usage.vacuum.nplanned,
+									 vacrel->workers_usage.vacuum.nreserved,
+									 vacrel->workers_usage.vacuum.nlaunched);
+				}
+				else
+				{
+					appendStringInfo(&buf,
+									 _("parallel workers: index vacuum: %d planned, %d launched in total\n"),
+									 vacrel->workers_usage.vacuum.nplanned,
+									 vacrel->workers_usage.vacuum.nlaunched);
+				}
+			}
+			if (vacrel->workers_usage.cleanup.nplanned > 0)
+			{
+				if (AmAutoVacuumWorkerProcess())
+				{
+					appendStringInfo(&buf,
+									 _("parallel workers: index cleanup: %d planned, %d reserved, %d launched\n"),
+									 vacrel->workers_usage.cleanup.nplanned,
+									 vacrel->workers_usage.cleanup.nreserved,
+									 vacrel->workers_usage.cleanup.nlaunched);
+				}
+				else
+				{
+					appendStringInfo(&buf,
+									 _("parallel workers: index cleanup: %d planned, %d launched\n"),
+									 vacrel->workers_usage.cleanup.nplanned,
+									 vacrel->workers_usage.cleanup.nlaunched);
+				}
+			}
 			for (int i = 0; i < vacrel->nindexes; i++)
 			{
 				IndexBulkDeleteResult *istat = vacrel->indstats[i];
@@ -2666,7 +2714,8 @@ lazy_vacuum_all_indexes(LVRelState *vacrel)
 	{
 		/* Outsource everything to parallel variant */
 		parallel_vacuum_bulkdel_all_indexes(vacrel->pvs, old_live_tuples,
-											vacrel->num_index_scans);
+											vacrel->num_index_scans,
+											&vacrel->workers_usage);
 
 		/*
 		 * Do a postcheck to consider applying wraparound failsafe now.  Note
@@ -3099,7 +3148,8 @@ lazy_cleanup_all_indexes(LVRelState *vacrel)
 		/* Outsource everything to parallel variant */
 		parallel_vacuum_cleanup_all_indexes(vacrel->pvs, reltuples,
 											vacrel->num_index_scans,
-											estimated_count);
+											estimated_count,
+											&vacrel->workers_usage);
 	}
 
 	/* Reset the progress counters */
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index 806a7f48326..643849b2fb8 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -228,7 +228,7 @@ struct ParallelVacuumState
 static int	parallel_vacuum_compute_workers(Relation *indrels, int nindexes, int nrequested,
 											bool *will_parallel_vacuum);
 static void parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scans,
-												bool vacuum);
+												bool vacuum, PVWorkersStats *wstats);
 static void parallel_vacuum_process_safe_indexes(ParallelVacuumState *pvs);
 static void parallel_vacuum_process_unsafe_indexes(ParallelVacuumState *pvs);
 static void parallel_vacuum_process_one_index(ParallelVacuumState *pvs, Relation indrel,
@@ -503,7 +503,7 @@ parallel_vacuum_reset_dead_items(ParallelVacuumState *pvs)
  */
 void
 parallel_vacuum_bulkdel_all_indexes(ParallelVacuumState *pvs, long num_table_tuples,
-									int num_index_scans)
+									int num_index_scans, PVWorkersUsage *wusage)
 {
 	Assert(!IsParallelWorker());
 
@@ -514,7 +514,8 @@ parallel_vacuum_bulkdel_all_indexes(ParallelVacuumState *pvs, long num_table_tup
 	pvs->shared->reltuples = num_table_tuples;
 	pvs->shared->estimated_count = true;
 
-	parallel_vacuum_process_all_indexes(pvs, num_index_scans, true);
+	parallel_vacuum_process_all_indexes(pvs, num_index_scans, true,
+										&wusage->vacuum);
 }
 
 /*
@@ -522,7 +523,8 @@ parallel_vacuum_bulkdel_all_indexes(ParallelVacuumState *pvs, long num_table_tup
  */
 void
 parallel_vacuum_cleanup_all_indexes(ParallelVacuumState *pvs, long num_table_tuples,
-									int num_index_scans, bool estimated_count)
+									int num_index_scans, bool estimated_count,
+									PVWorkersUsage *wusage)
 {
 	Assert(!IsParallelWorker());
 
@@ -534,7 +536,8 @@ parallel_vacuum_cleanup_all_indexes(ParallelVacuumState *pvs, long num_table_tup
 	pvs->shared->reltuples = num_table_tuples;
 	pvs->shared->estimated_count = estimated_count;
 
-	parallel_vacuum_process_all_indexes(pvs, num_index_scans, false);
+	parallel_vacuum_process_all_indexes(pvs, num_index_scans, false,
+										&wusage->cleanup);
 }
 
 /*
@@ -616,10 +619,13 @@ parallel_vacuum_compute_workers(Relation *indrels, int nindexes, int nrequested,
 /*
  * Perform index vacuum or index cleanup with parallel workers.  This function
  * must be used by the parallel vacuum leader process.
+ *
+ * If wstats is not NULL, the statistics it stores will be updated according
+ * to what happens during function execution.
  */
 static void
 parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scans,
-									bool vacuum)
+									bool vacuum, PVWorkersStats *wstats)
 {
 	int			nworkers;
 	PVIndVacStatus new_status;
@@ -656,13 +662,23 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
 	 */
 	nworkers = Min(nworkers, pvs->pcxt->nworkers);
 
+	/* Remember this value, if we asked to */
+	if (wstats != NULL && nworkers > 0)
+		wstats->nplanned += nworkers;
+
 	/*
 	 * Reserve workers in autovacuum global state. Note that we may be given
 	 * fewer workers than we requested.
 	 */
 	if (AmAutoVacuumWorkerProcess() && nworkers > 0)
+	{
 		AutoVacuumReserveParallelWorkers(&nworkers);
 
+		/* Remember this value, if we asked to */
+		if (wstats != NULL)
+			wstats->nreserved += nworkers;
+	}
+
 	/*
 	 * Set index vacuum status and mark whether parallel vacuum worker can
 	 * process it.
@@ -729,6 +745,10 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
 			/* Enable shared cost balance for leader backend */
 			VacuumSharedCostBalance = &(pvs->shared->cost_balance);
 			VacuumActiveNWorkers = &(pvs->shared->active_nworkers);
+
+			/* Remember this value, if we asked to */
+			if (wstats != NULL)
+				wstats->nlaunched += pvs->pcxt->nworkers_launched;
 		}
 
 		if (vacuum)
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index e885a4b9c77..1b1fb625cb2 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -300,6 +300,39 @@ typedef struct VacDeadItemsInfo
 	int64		num_items;		/* current # of entries */
 } VacDeadItemsInfo;
 
+/*
+ * Helper for the PVWorkersUsage structure (see below), to avoid repetition.
+ */
+typedef struct PVWorkersStats
+{
+	/* Number of parallel workers we are planned to launch */
+	int			nplanned;
+
+	/*
+	 * Number of parallel workers we have managed to reserve.
+	 *
+	 * Note, that we collect this stats only for the parallel *autovacuum*
+	 * since during it we must reserve workers in shared state before actually
+	 * trying to launch them (in order to meet the
+	 * autovacuum_max_parallel_workers limit). Manual VACUUM (PARALLEL), on
+	 * the contrary, doesn't need to reserve workers.
+	 */
+	int			nreserved;
+
+	/* Number of launched parallel workers */
+	int			nlaunched;
+} PVWorkersStats;
+
+/*
+ * PVWorkersUsage stores information about total number of launched, reserved
+ * and planned workers during parallel vacuum (both for vacuum and cleanup).
+ */
+typedef struct PVWorkersUsage
+{
+	PVWorkersStats vacuum;
+	PVWorkersStats cleanup;
+} PVWorkersUsage;
+
 /* GUC parameters */
 extern PGDLLIMPORT int default_statistics_target;	/* PGDLLIMPORT for PostGIS */
 extern PGDLLIMPORT int vacuum_freeze_min_age;
@@ -394,11 +427,13 @@ extern TidStore *parallel_vacuum_get_dead_items(ParallelVacuumState *pvs,
 extern void parallel_vacuum_reset_dead_items(ParallelVacuumState *pvs);
 extern void parallel_vacuum_bulkdel_all_indexes(ParallelVacuumState *pvs,
 												long num_table_tuples,
-												int num_index_scans);
+												int num_index_scans,
+												PVWorkersUsage *wusage);
 extern void parallel_vacuum_cleanup_all_indexes(ParallelVacuumState *pvs,
 												long num_table_tuples,
 												int num_index_scans,
-												bool estimated_count);
+												bool estimated_count,
+												PVWorkersUsage *wusage);
 extern void parallel_vacuum_main(dsm_segment *seg, shm_toc *toc);
 
 /* in commands/analyze.c */
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 77e3c04144e..536237ff546 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2070,6 +2070,8 @@ PVIndStats
 PVIndVacStatus
 PVOID
 PVShared
+PVWorkersUsage
+PVWorkersStats
 PX_Alias
 PX_Cipher
 PX_Combo
-- 
2.43.0