Hi,
On Mon, Jul 21, 2025 at 11:40 PM Sami Imseih <samims...@gmail.com> wrote:
>
> I have only reviewed the v8-0001-Parallel-index-autovacuum.patch so far and
> have a few comments from my initial pass.
>
> 1/ Please run pgindent.
OK, I'll do it.
> 2/ Documentation is missing. There may be more, but here are the places I
> found that likely need updates for the new behavior, reloptions, GUC, etc.
> Including docs in the patch early would help clarify expected behavior.
>
> https://www.postgresql.org/docs/current/routine-vacuuming.html#VACUUM-BASICS
> https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM
> https://www.postgresql.org/docs/current/runtime-config-autovacuum.html
> https://www.postgresql.org/docs/current/sql-createtable.html
> https://www.postgresql.org/docs/current/sql-altertable.html
> https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-MAX-WORKER-PROCESSES
> https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-MAX-PARALLEL-MAINTENANCE-WORKERS
>
Thanks for gathering it all together. I'll update the documentation so
it will reflect changes in autovacuum daemon, reloptions and GUC
parameters. So far, I don't see what we can add to vacuum-basics
and alter-table paragraphs.
I'll create separate .patch file for changes in documentation.
> One thing I am unclear on is the interaction between max_worker_processes,
> max_parallel_workers, and max_parallel_maintenance_workers. For example, does
> the following change mean that manual VACUUM PARALLEL is no longer capped by
> max_parallel_maintenance_workers?
>
> @@ -597,8 +614,8 @@ parallel_vacuum_compute_workers(Relation *indrels,
> int nindexes, int nrequested,
> parallel_workers = (nrequested > 0) ?
> Min(nrequested, nindexes_parallel) : nindexes_parallel;
>
> - /* Cap by max_parallel_maintenance_workers */
> - parallel_workers = Min(parallel_workers,
> max_parallel_maintenance_workers);
> + /* Cap by GUC variable */
> + parallel_workers = Min(parallel_workers, max_parallel_workers);
>
Oh, it is my poor choice of a name for a local variable (I'll rename it).
This variable can get different values depending on performed operation :
autovacuum_max_parallel_workers for parallel autovacuum and
max_parallel_maintenance_workers for maintenance VACUUM.
>
> 3/ Shouldn't this be "max_parallel_workers" instead of "bgworkers pool" ?
>
> + "autovacuum_parallel_workers",
> + "Maximum number of parallel autovacuum workers
> that can be taken from bgworkers pool for processing this table. "
>
I don't think that we should refer to max_parallel_workers here.
Actually, this reloption doesn't depend on max_parallel_workers at all.
I wrote about bgworkers pool (both here and in description of
autovacuum_max_parallel_workers parameter) in order to clarify that
parallel autovacuum will use dynamic workers instead of launching
more a/v workers.
BTW, I don't really like that the comment on this option turns out to be
very large. I'll leave only short description in reloptions.c and move
clarification about zero value in rel.h
Mentions of bgworkers pool will remain only in
description of autovacuum_max_parallel_workers.
> 4/ The comment "When parallel autovacuum worker die" suggests an abnormal
> exit. "Terminates" seems clearer, since this applies to both normal and
> abnormal exits.
>
> instead of:
> + * When parallel autovacuum worker die,
>
> how about this:
> * When parallel autovacuum worker terminates,
>
Sounds reasonable, I'll fix it.
>
> 5/ Any reason AutoVacuumReleaseParallelWorkers cannot be called before
> DestroyParallelContext?
>
> + nlaunched_workers = pvs->pcxt->nworkers_launched; /* remember
> this value */
> DestroyParallelContext(pvs->pcxt);
> +
> + /* Release all launched (i.e. reserved) parallel autovacuum workers.
> */
> + if (AmAutoVacuumWorkerProcess())
> + AutoVacuumReleaseParallelWorkers(nlaunched_workers);
>
I wrote about it above [1], but I think I can duplicate my thoughts here :
"""
Destroying parallel context includes waiting for all workers to exit (after
which, other operations can use them).
If we first call ParallelAutoVacuumReleaseWorkers, some operation can
reasonably request all released workers. But this request can fail,
because there is no guarantee that workers managed to finish.
Actually, there's nothing wrong with that, but I think releasing workers
only after finishing work is a more logical approach.
"""
>
> 6/ Also, would it be cleaner to move AmAutoVacuumWorkerProcess() inside
> AutoVacuumReleaseParallelWorkers()?
>
> if (!AmAutoVacuumWorkerProcess())
> return;
>
It seems to me that the opposite is true. If there is no alternative to calling
AmAutoVacuumWorkerProcess, it might confuse somebody. All doubts
will disappear after viewing the AmAutoVacuumWorkerProcess code,
but IMO code in vacuumparallel.c will become less intuitive.
> 7/ It looks like the psql tab completion for autovacuum_parallel_workers is
> missing:
>
> test=# alter table t set (autovacuum_
> autovacuum_analyze_scale_factor
> autovacuum_analyze_threshold
> autovacuum_enabled
> autovacuum_freeze_max_age
> autovacuum_freeze_min_age
> autovacuum_freeze_table_age
> autovacuum_multixact_freeze_max_age
> autovacuum_multixact_freeze_min_age
> autovacuum_multixact_freeze_table_age
> autovacuum_vacuum_cost_delay
> autovacuum_vacuum_cost_limit
> autovacuum_vacuum_insert_scale_factor
> autovacuum_vacuum_insert_threshold
> autovacuum_vacuum_max_threshold
> autovacuum_vacuum_scale_factor
> autovacuum_vacuum_threshold
>
Good catch, I'll fix it.
Thank you for the review! Please, see v9 patches :
1) Run pgindent + rebase patches on newest commit in master.
2) Introduce changes for documentation.
3) Rename local variable in parallel_vacuum_compute_workers.
4) Shorten the description of autovacuum_parallel_workers in
reloptions.c (move clarifications for it into rel.h).
5) Reword "When parallel autovacuum worker die" comment.
6) Add tab completion for autovacuum_parallel_workers table option.
[1]
https://www.postgresql.org/message-id/CAJDiXgi7KB7wSQ%3DUx%3DngdaCvJnJ5x-ehvTyiuZez%2B5uKHtV6iQ%40mail.gmail.com
--
Best regards,
Daniil Davydov
From 1c4c65cad27e2986962ef0d041bf4f332c58f668 Mon Sep 17 00:00:00 2001
From: Daniil Davidov <d.davy...@postgrespro.ru>
Date: Tue, 22 Jul 2025 02:47:24 +0700
Subject: [PATCH v9 2/3] Logging for parallel autovacuum
---
src/backend/access/heap/vacuumlazy.c | 27 +++++++++++++++++++++++++--
src/backend/commands/vacuumparallel.c | 20 ++++++++++++++------
src/include/commands/vacuum.h | 16 ++++++++++++++--
3 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 14036c27e87..f1a645e79a9 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -348,6 +348,12 @@ typedef struct LVRelState
/* Instrumentation counters */
int num_index_scans;
+
+ /*
+ * Number of planned and actually launched parallel workers for all index
+ * scans, or NULL
+ */
+ PVWorkersUsage *workers_usage;
/* Counters that follow are only for scanned_pages */
int64 tuples_deleted; /* # deleted from table */
int64 tuples_frozen; /* # newly frozen */
@@ -688,6 +694,16 @@ heap_vacuum_rel(Relation rel, const VacuumParams params,
indnames = palloc(sizeof(char *) * vacrel->nindexes);
for (int i = 0; i < vacrel->nindexes; i++)
indnames[i] = pstrdup(RelationGetRelationName(vacrel->indrels[i]));
+
+ /*
+ * Allocate space for workers usage statistics. Thus, we explicitly
+ * make clear that such statistics must be accumulated. For now, this
+ * is used only by autovacuum leader worker, because it must log it in
+ * the end of table processing.
+ */
+ vacrel->workers_usage = AmAutoVacuumWorkerProcess() ?
+ (PVWorkersUsage *) palloc0(sizeof(PVWorkersUsage)) :
+ NULL;
}
/*
@@ -1012,6 +1028,11 @@ heap_vacuum_rel(Relation rel, const VacuumParams params,
vacrel->relnamespace,
vacrel->relname,
vacrel->num_index_scans);
+ if (vacrel->workers_usage)
+ appendStringInfo(&buf,
+ _("workers usage statistics for all of index scans : launched in total = %d, planned in total = %d\n"),
+ vacrel->workers_usage->nlaunched,
+ vacrel->workers_usage->nplanned);
appendStringInfo(&buf, _("pages: %u removed, %u remain, %u scanned (%.2f%% of total), %u eagerly scanned\n"),
vacrel->removed_pages,
new_rel_pages,
@@ -2634,7 +2655,8 @@ 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
@@ -3047,7 +3069,8 @@ 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 ffc140dabcf..51511bf2100 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -227,7 +227,7 @@ 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, PVWorkersUsage * wusage);
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,
@@ -510,7 +510,7 @@ 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());
@@ -521,7 +521,7 @@ 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);
}
/*
@@ -529,7 +529,8 @@ 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());
@@ -541,7 +542,7 @@ 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);
}
/*
@@ -626,7 +627,7 @@ parallel_vacuum_compute_workers(Relation *indrels, int nindexes, int nrequested,
*/
static void
parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scans,
- bool vacuum)
+ bool vacuum, PVWorkersUsage * wusage)
{
int nworkers;
PVIndVacStatus new_status;
@@ -750,6 +751,13 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
"launched %d parallel vacuum workers for index cleanup (planned: %d)",
pvs->pcxt->nworkers_launched),
pvs->pcxt->nworkers_launched, nworkers)));
+
+ /* Remember these values, if we asked to. */
+ if (wusage != NULL)
+ {
+ wusage->nlaunched += pvs->pcxt->nworkers_launched;
+ wusage->nplanned += nworkers;
+ }
}
/* Vacuum the indexes that can be processed by only leader process */
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index 14eeccbd718..d05ef7461ea 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -295,6 +295,16 @@ typedef struct VacDeadItemsInfo
int64 num_items; /* current # of entries */
} VacDeadItemsInfo;
+/*
+ * PVWorkersUsage stores information about total number of launched and planned
+ * workers during parallel vacuum.
+ */
+typedef struct PVWorkersUsage
+{
+ int nlaunched;
+ int nplanned;
+} PVWorkersUsage;
+
/* GUC parameters */
extern PGDLLIMPORT int default_statistics_target; /* PGDLLIMPORT for PostGIS */
extern PGDLLIMPORT int vacuum_freeze_min_age;
@@ -389,11 +399,13 @@ 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 */
--
2.43.0
From de46c8232641e288a46e6af1799961c1b00a4655 Mon Sep 17 00:00:00 2001
From: Daniil Davidov <d.davy...@postgrespro.ru>
Date: Tue, 22 Jul 2025 12:31:20 +0700
Subject: [PATCH v9 3/3] Documentation for parallel autovacuum
---
doc/src/sgml/config.sgml | 18 ++++++++++++++++++
doc/src/sgml/maintenance.sgml | 12 ++++++++++++
doc/src/sgml/ref/create_table.sgml | 20 ++++++++++++++++++++
3 files changed, 50 insertions(+)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index c7acc0f182f..06b0aff6cb7 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2835,6 +2835,7 @@ include_dir 'conf.d'
<para>
When changing this value, consider also adjusting
<xref linkend="guc-max-parallel-workers"/>,
+ <xref linkend="guc-autovacuum-max-parallel-workers"/>,
<xref linkend="guc-max-parallel-maintenance-workers"/>, and
<xref linkend="guc-max-parallel-workers-per-gather"/>.
</para>
@@ -9187,6 +9188,23 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
</listitem>
</varlistentry>
+ <varlistentry id="guc-autovacuum-max-parallel-workers" xreflabel="autovacuum_max_parallel_workers">
+ <term><varname>autovacuum_max_parallel_workers</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>autovacuum_max_parallel_workers</varname></primary>
+ <secondary>configuration parameter</secondary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Sets the maximum number of parallel autovacuum workers that
+ can be used for parallel index vacuuming at one time. Is capped by
+ <xref linkend="guc-max-worker-processes"/>. The default is 0,
+ which means no parallel index vacuuming.
+ </para>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect2>
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index e7a9f58c015..4e450ba9066 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -896,6 +896,18 @@ HINT: Execute a database-wide VACUUM in that database.
autovacuum workers' activity.
</para>
+ <para>
+ If an autovacuum worker process comes across a table with the enabled
+ <xref linkend="reloption-autovacuum-parallel-workers"/> storage parameter,
+ it will launch parallel workers in order to vacuum indexes of this table
+ in a parallel mode. Parallel workers are taken from the pool of processes
+ established by <xref linkend="guc-max-worker-processes"/>, limited by
+ <xref linkend="guc-max-parallel-workers"/>.
+ The total number of parallel autovacuum workers that can be active at one
+ time is limited by the <xref linkend="guc-autovacuum-max-parallel-workers"/>
+ configuration parameter.
+ </para>
+
<para>
If several large tables all become eligible for vacuuming in a short
amount of time, all autovacuum workers might become occupied with
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index dc000e913c1..288de6b0ffd 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1717,6 +1717,26 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
</listitem>
</varlistentry>
+ <varlistentry id="reloption-autovacuum-parallel-workers" xreflabel="autovacuum_parallel_workers">
+ <term><literal>autovacuum_parallel_workers</literal> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>autovacuum_parallel_workers</varname> storage parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Sets the maximum number of parallel autovacuum workers that can process
+ indexes of this table.
+ The default value is -1, which means no parallel index vacuuming for
+ this table. If value is 0 then parallel degree will computed based on
+ number of indexes.
+ Note that the computed number of workers may not actually be available at
+ run time. If this occurs, the autovacuum will run with fewer workers
+ than expected.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="reloption-autovacuum-vacuum-threshold" xreflabel="autovacuum_vacuum_threshold">
<term><literal>autovacuum_vacuum_threshold</literal>, <literal>toast.autovacuum_vacuum_threshold</literal> (<type>integer</type>)
<indexterm>
--
2.43.0
From f5e21f44faa8618bfd575099317ecf06213f62f0 Mon Sep 17 00:00:00 2001
From: Daniil Davidov <d.davy...@postgrespro.ru>
Date: Sun, 20 Jul 2025 23:03:57 +0700
Subject: [PATCH v9 1/3] Parallel index autovacuum
---
src/backend/access/common/reloptions.c | 11 ++
src/backend/commands/vacuumparallel.c | 46 ++++++-
src/backend/postmaster/autovacuum.c | 121 +++++++++++++++++-
src/backend/utils/init/globals.c | 1 +
src/backend/utils/misc/guc_tables.c | 10 ++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/bin/psql/tab-complete.in.c | 1 +
src/include/miscadmin.h | 1 +
src/include/postmaster/autovacuum.h | 4 +
src/include/utils/guc_hooks.h | 1 +
src/include/utils/rel.h | 7 +
11 files changed, 196 insertions(+), 8 deletions(-)
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 50747c16396..cc3ffc43a05 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -222,6 +222,15 @@ static relopt_int intRelOpts[] =
},
SPGIST_DEFAULT_FILLFACTOR, SPGIST_MIN_FILLFACTOR, 100
},
+ {
+ {
+ "autovacuum_parallel_workers",
+ "Maximum number of parallel autovacuum workers that can be used for processing this table.",
+ RELOPT_KIND_HEAP,
+ ShareUpdateExclusiveLock
+ },
+ -1, -1, 1024
+ },
{
{
"autovacuum_vacuum_threshold",
@@ -1872,6 +1881,8 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
{"fillfactor", RELOPT_TYPE_INT, offsetof(StdRdOptions, fillfactor)},
{"autovacuum_enabled", RELOPT_TYPE_BOOL,
offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, enabled)},
+ {"autovacuum_parallel_workers", RELOPT_TYPE_INT,
+ offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, autovacuum_parallel_workers)},
{"autovacuum_vacuum_threshold", RELOPT_TYPE_INT,
offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_threshold)},
{"autovacuum_vacuum_max_threshold", RELOPT_TYPE_INT,
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index 0feea1d30ec..ffc140dabcf 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -1,7 +1,9 @@
/*-------------------------------------------------------------------------
*
* vacuumparallel.c
- * Support routines for parallel vacuum execution.
+ * Support routines for parallel vacuum and autovacuum execution. In the
+ * future comments, the word "vacuum" will refer to both vacuum and
+ * autovacuum.
*
* This file contains routines that are intended to support setting up, using,
* and tearing down a ParallelVacuumState.
@@ -34,6 +36,7 @@
#include "executor/instrument.h"
#include "optimizer/paths.h"
#include "pgstat.h"
+#include "postmaster/autovacuum.h"
#include "storage/bufmgr.h"
#include "tcop/tcopprot.h"
#include "utils/lsyscache.h"
@@ -373,8 +376,9 @@ parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,
shared->queryid = pgstat_get_my_query_id();
shared->maintenance_work_mem_worker =
(nindexes_mwm > 0) ?
- maintenance_work_mem / Min(parallel_workers, nindexes_mwm) :
- maintenance_work_mem;
+ vac_work_mem / Min(parallel_workers, nindexes_mwm) :
+ vac_work_mem;
+
shared->dead_items_info.max_bytes = vac_work_mem * (size_t) 1024;
/* Prepare DSA space for dead items */
@@ -435,6 +439,8 @@ parallel_vacuum_init(Relation rel, Relation *indrels, int nindexes,
void
parallel_vacuum_end(ParallelVacuumState *pvs, IndexBulkDeleteResult **istats)
{
+ int nlaunched_workers;
+
Assert(!IsParallelWorker());
/* Copy the updated statistics */
@@ -453,7 +459,13 @@ parallel_vacuum_end(ParallelVacuumState *pvs, IndexBulkDeleteResult **istats)
TidStoreDestroy(pvs->dead_items);
+ nlaunched_workers = pvs->pcxt->nworkers_launched; /* remember this value */
DestroyParallelContext(pvs->pcxt);
+
+ /* Release all launched (i.e. reserved) parallel autovacuum workers. */
+ if (AmAutoVacuumWorkerProcess())
+ AutoVacuumReleaseParallelWorkers(nlaunched_workers);
+
ExitParallelMode();
pfree(pvs->will_parallel_vacuum);
@@ -553,12 +565,17 @@ parallel_vacuum_compute_workers(Relation *indrels, int nindexes, int nrequested,
int nindexes_parallel_bulkdel = 0;
int nindexes_parallel_cleanup = 0;
int parallel_workers;
+ int max_workers;
+
+ max_workers = AmAutoVacuumWorkerProcess() ?
+ autovacuum_max_parallel_workers :
+ max_parallel_maintenance_workers;
/*
* We don't allow performing parallel operation in standalone backend or
* when parallelism is disabled.
*/
- if (!IsUnderPostmaster || max_parallel_maintenance_workers == 0)
+ if (!IsUnderPostmaster || max_workers == 0)
return 0;
/*
@@ -597,8 +614,8 @@ parallel_vacuum_compute_workers(Relation *indrels, int nindexes, int nrequested,
parallel_workers = (nrequested > 0) ?
Min(nrequested, nindexes_parallel) : nindexes_parallel;
- /* Cap by max_parallel_maintenance_workers */
- parallel_workers = Min(parallel_workers, max_parallel_maintenance_workers);
+ /* Cap by GUC variable */
+ parallel_workers = Min(parallel_workers, max_workers);
return parallel_workers;
}
@@ -646,6 +663,13 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
*/
nworkers = Min(nworkers, pvs->pcxt->nworkers);
+ /*
+ * Also reserve workers in autovacuum global state. Note, that we may be
+ * given fewer workers than we requested.
+ */
+ if (AmAutoVacuumWorkerProcess() && nworkers > 0)
+ nworkers = AutoVacuumReserveParallelWorkers(nworkers);
+
/*
* Set index vacuum status and mark whether parallel vacuum worker can
* process it.
@@ -690,6 +714,16 @@ parallel_vacuum_process_all_indexes(ParallelVacuumState *pvs, int num_index_scan
LaunchParallelWorkers(pvs->pcxt);
+ if (AmAutoVacuumWorkerProcess() &&
+ pvs->pcxt->nworkers_launched < nworkers)
+ {
+ /*
+ * Tell autovacuum that we could not launch all the previously
+ * reserved workers.
+ */
+ AutoVacuumReleaseParallelWorkers(nworkers - pvs->pcxt->nworkers_launched);
+ }
+
if (pvs->pcxt->nworkers_launched > 0)
{
/*
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 9474095f271..76eb04029a3 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -285,6 +285,7 @@ typedef struct AutoVacuumWorkItem
* av_workItems work item array
* av_nworkersForBalance the number of autovacuum workers to use when
* calculating the per worker cost limit
+ * av_freeParallelWorkers the number of free parallel autovacuum workers
*
* This struct is protected by AutovacuumLock, except for av_signal and parts
* of the worker list (see above).
@@ -299,6 +300,7 @@ typedef struct
WorkerInfo av_startingWorker;
AutoVacuumWorkItem av_workItems[NUM_WORKITEMS];
pg_atomic_uint32 av_nworkersForBalance;
+ uint32 av_freeParallelWorkers;
} AutoVacuumShmemStruct;
static AutoVacuumShmemStruct *AutoVacuumShmem;
@@ -354,6 +356,7 @@ static void autovac_report_workitem(AutoVacuumWorkItem *workitem,
static void avl_sigusr2_handler(SIGNAL_ARGS);
static bool av_worker_available(void);
static void check_av_worker_gucs(void);
+static void adjust_free_parallel_workers(int prev_max_parallel_workers);
@@ -753,6 +756,8 @@ ProcessAutoVacLauncherInterrupts(void)
if (ConfigReloadPending)
{
int autovacuum_max_workers_prev = autovacuum_max_workers;
+ int autovacuum_max_parallel_workers_prev =
+ autovacuum_max_parallel_workers;
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
@@ -769,6 +774,15 @@ ProcessAutoVacLauncherInterrupts(void)
if (autovacuum_max_workers_prev != autovacuum_max_workers)
check_av_worker_gucs();
+ /*
+ * If autovacuum_max_parallel_workers changed, we must take care of
+ * the correct value of available parallel autovacuum workers in
+ * shmem.
+ */
+ if (autovacuum_max_parallel_workers_prev !=
+ autovacuum_max_parallel_workers)
+ adjust_free_parallel_workers(autovacuum_max_parallel_workers_prev);
+
/* rebuild the list in case the naptime changed */
rebuild_database_list(InvalidOid);
}
@@ -2847,8 +2861,12 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
*/
tab->at_params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
tab->at_params.truncate = VACOPTVALUE_UNSPECIFIED;
- /* As of now, we don't support parallel vacuum for autovacuum */
- tab->at_params.nworkers = -1;
+
+ /* Decide whether we need to process indexes of table in parallel. */
+ tab->at_params.nworkers = avopts
+ ? avopts->autovacuum_parallel_workers
+ : -1;
+
tab->at_params.freeze_min_age = freeze_min_age;
tab->at_params.freeze_table_age = freeze_table_age;
tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
@@ -3329,6 +3347,68 @@ AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
return result;
}
+/*
+ * In order to meet the 'autovacuum_max_parallel_workers' limit, leader worker
+ * must call this function. It returns the number of parallel workers that
+ * actually can be launched and reserves (if any) these workers in global
+ * autovacuum state.
+ *
+ * NOTE: We will try to provide as many workers as requested, even if caller
+ * will occupy all available workers.
+ */
+int
+AutoVacuumReserveParallelWorkers(int nworkers)
+{
+ int can_launch;
+
+ /* Only leader worker can call this function. */
+ Assert(AmAutoVacuumWorkerProcess() && !IsParallelWorker());
+
+ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
+
+ /* Provide as many workers as we can. */
+ can_launch = Min(AutoVacuumShmem->av_freeParallelWorkers, nworkers);
+ AutoVacuumShmem->av_freeParallelWorkers -= nworkers;
+
+ LWLockRelease(AutovacuumLock);
+ return can_launch;
+}
+
+/*
+ * When parallel autovacuum worker terminates, leader worker must call this
+ * function in order to refresh global autovacuum state. Thus, other leaders
+ * will be able to use these workers.
+ *
+ * 'nworkers' - how many workers caller wants to release.
+ */
+void
+AutoVacuumReleaseParallelWorkers(int nworkers)
+{
+ /* Only leader worker can call this function. */
+ Assert(AmAutoVacuumWorkerProcess() && !IsParallelWorker());
+
+ /* Refresh autovacuum_max_parallel_workers paremeter */
+ CHECK_FOR_INTERRUPTS();
+ if (ConfigReloadPending)
+ {
+ ConfigReloadPending = false;
+ ProcessConfigFile(PGC_SIGHUP);
+ }
+
+ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
+
+ /*
+ * If autovacuum_max_parallel_workers parameter was reduced during
+ * parallel autovacuum execution, we must cap available workers number by
+ * its new value.
+ */
+ AutoVacuumShmem->av_freeParallelWorkers =
+ Min(AutoVacuumShmem->av_freeParallelWorkers + nworkers,
+ autovacuum_max_parallel_workers);
+
+ LWLockRelease(AutovacuumLock);
+}
+
/*
* autovac_init
* This is called at postmaster initialization.
@@ -3389,6 +3469,8 @@ AutoVacuumShmemInit(void)
Assert(!found);
AutoVacuumShmem->av_launcherpid = 0;
+ AutoVacuumShmem->av_freeParallelWorkers =
+ autovacuum_max_parallel_workers;
dclist_init(&AutoVacuumShmem->av_freeWorkers);
dlist_init(&AutoVacuumShmem->av_runningWorkers);
AutoVacuumShmem->av_startingWorker = NULL;
@@ -3439,6 +3521,12 @@ check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
return true;
}
+void
+assign_autovacuum_max_parallel_workers(int newval, void *extra)
+{
+ autovacuum_max_parallel_workers = Min(newval, max_worker_processes);
+}
+
/*
* Returns whether there is a free autovacuum worker slot available.
*/
@@ -3470,3 +3558,32 @@ check_av_worker_gucs(void)
errdetail("The server will only start up to \"autovacuum_worker_slots\" (%d) autovacuum workers at a given time.",
autovacuum_worker_slots)));
}
+
+/*
+ * Make sure that number of free parallel workers corresponds to the
+ * autovacuum_max_parallel_workers parameter (after it was changed).
+ */
+static void
+adjust_free_parallel_workers(int prev_max_parallel_workers)
+{
+ LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
+
+ /*
+ * Cap the number of free workers by new parameter's value, if needed.
+ */
+ AutoVacuumShmem->av_freeParallelWorkers =
+ Min(AutoVacuumShmem->av_freeParallelWorkers,
+ autovacuum_max_parallel_workers);
+
+ if (autovacuum_max_parallel_workers > prev_max_parallel_workers)
+ {
+ /*
+ * If user wants to increase number of parallel autovacuum workers, we
+ * must increase number of free workers.
+ */
+ AutoVacuumShmem->av_freeParallelWorkers +=
+ (autovacuum_max_parallel_workers - prev_max_parallel_workers);
+ }
+
+ LWLockRelease(AutovacuumLock);
+}
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index d31cb45a058..fd00d6f89dc 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -143,6 +143,7 @@ int NBuffers = 16384;
int MaxConnections = 100;
int max_worker_processes = 8;
int max_parallel_workers = 8;
+int autovacuum_max_parallel_workers = 0;
int MaxBackends = 0;
/* GUC parameters for vacuum */
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index d14b1678e7f..4941ad976df 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -3604,6 +3604,16 @@ struct config_int ConfigureNamesInt[] =
NULL, NULL, NULL
},
+ {
+ {"autovacuum_max_parallel_workers", PGC_SIGHUP, VACUUM_AUTOVACUUM,
+ gettext_noop("Maximum number of parallel autovacuum workers, that can be taken from bgworkers pool."),
+ gettext_noop("This parameter is capped by \"max_worker_processes\" (not by \"autovacuum_max_workers\"!)."),
+ },
+ &autovacuum_max_parallel_workers,
+ 0, 0, MAX_BACKENDS,
+ NULL, assign_autovacuum_max_parallel_workers, NULL
+ },
+
{
{"max_parallel_maintenance_workers", PGC_USERSET, RESOURCES_WORKER_PROCESSES,
gettext_noop("Sets the maximum number of parallel processes per maintenance operation."),
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index a9d8293474a..bbf5307000f 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -683,6 +683,7 @@
autovacuum_worker_slots = 16 # autovacuum worker slots to allocate
# (change requires restart)
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
+#autovacuum_max_parallel_workers = 0 # disabled by default and limited by max_worker_processes
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 37524364290..3b3d4438e65 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -1399,6 +1399,7 @@ static const char *const table_storage_parameters[] = {
"autovacuum_multixact_freeze_max_age",
"autovacuum_multixact_freeze_min_age",
"autovacuum_multixact_freeze_table_age",
+ "autovacuum_parallel_workers",
"autovacuum_vacuum_cost_delay",
"autovacuum_vacuum_cost_limit",
"autovacuum_vacuum_insert_scale_factor",
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 1bef98471c3..85926415657 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -177,6 +177,7 @@ extern PGDLLIMPORT int MaxBackends;
extern PGDLLIMPORT int MaxConnections;
extern PGDLLIMPORT int max_worker_processes;
extern PGDLLIMPORT int max_parallel_workers;
+extern PGDLLIMPORT int autovacuum_max_parallel_workers;
extern PGDLLIMPORT int commit_timestamp_buffers;
extern PGDLLIMPORT int multixact_member_buffers;
diff --git a/src/include/postmaster/autovacuum.h b/src/include/postmaster/autovacuum.h
index e8135f41a1c..42d4a63d033 100644
--- a/src/include/postmaster/autovacuum.h
+++ b/src/include/postmaster/autovacuum.h
@@ -64,6 +64,10 @@ pg_noreturn extern void AutoVacWorkerMain(const void *startup_data, size_t start
extern bool AutoVacuumRequestWork(AutoVacuumWorkItemType type,
Oid relationId, BlockNumber blkno);
+/* parallel autovacuum stuff */
+extern int AutoVacuumReserveParallelWorkers(int nworkers);
+extern void AutoVacuumReleaseParallelWorkers(int nworkers);
+
/* shared memory stuff */
extern Size AutoVacuumShmemSize(void);
extern void AutoVacuumShmemInit(void);
diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h
index 82ac8646a8d..04833b4f147 100644
--- a/src/include/utils/guc_hooks.h
+++ b/src/include/utils/guc_hooks.h
@@ -31,6 +31,7 @@ extern void assign_application_name(const char *newval, void *extra);
extern const char *show_archive_command(void);
extern bool check_autovacuum_work_mem(int *newval, void **extra,
GucSource source);
+extern void assign_autovacuum_max_parallel_workers(int newval, void *extra);
extern bool check_vacuum_buffer_usage_limit(int *newval, void **extra,
GucSource source);
extern bool check_backtrace_functions(char **newval, void **extra,
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index b552359915f..edd286808bf 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -311,6 +311,13 @@ typedef struct ForeignKeyCacheInfo
typedef struct AutoVacOpts
{
bool enabled;
+
+ /*
+ * Max number of parallel autovacuum workers. If value is 0 then parallel
+ * degree will computed based on number of indexes.
+ */
+ int autovacuum_parallel_workers;
+
int vacuum_threshold;
int vacuum_max_threshold;
int vacuum_ins_threshold;
--
2.43.0
