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Fix per-relation memory leakage in autovacuum.

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PgStat_StatTabEntry and AutoVacOpts structs were leaked until
the end of the autovacuum worker's run, which is bad news if
there are a lot of relations in the database.

Note: pfree'ing the PgStat_StatTabEntry structs here seems a bit
risky, because pgstat_fetch_stat_tabentry_ext does not guarantee
anything about whether its result is long-lived.  It appears okay
so long as autovacuum forces PGSTAT_FETCH_CONSISTENCY_NONE, but
I think that API could use a re-think.

Also ensure that the VacuumRelation structure passed to
vacuum() is in recoverable storage.

Back-patch to v15 where we started to manage table statistics
this way.  (The AutoVacOpts leakage is probably older, but
I'm not excited enough to worry about just that part.)

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/285483.1746756246@sss.pgh.pa.us
Backpatch-through: 15
This commit is contained in:
Tom Lane 2025-05-23 14:43:44 -04:00
parent ee58de1008
commit e087b5b794
1 changed files with 41 additions and 11 deletions
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52
src/backend/postmaster/autovacuum.c
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@ -2211,6 +2211,12 @@ do_autovacuum(void)
}
}
}
/* Release stuff to avoid per-relation leakage */
if (relopts)
pfree(relopts);
if (tabentry)
pfree(tabentry);
}
table_endscan(relScan);
@ -2227,7 +2233,8 @@ do_autovacuum(void)
Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
PgStat_StatTabEntry *tabentry;
Oid relid;
AutoVacOpts *relopts = NULL;
AutoVacOpts *relopts;
bool free_relopts = false;
bool dovacuum;
bool doanalyze;
bool wraparound;
@ -2245,7 +2252,9 @@ do_autovacuum(void)
* main rel
*/
relopts = extract_autovac_opts(tuple, pg_class_desc);
if (relopts == NULL)
if (relopts)
free_relopts = true;
else
{
av_relation *hentry;
bool found;
@ -2266,6 +2275,12 @@ do_autovacuum(void)
/* ignore analyze for toast tables */
if (dovacuum)
table_oids = lappend_oid(table_oids, relid);
/* Release stuff to avoid leakage */
if (free_relopts)
pfree(relopts);
if (tabentry)
pfree(tabentry);
}
table_endscan(relScan);
@ -2637,6 +2652,8 @@ deleted:
pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
}
list_free(table_oids);
/*
* Perform additional work items, as requested by backends.
*/
@ -2818,8 +2835,8 @@ deleted2:
/*
* extract_autovac_opts
*
* Given a relation's pg_class tuple, return the AutoVacOpts portion of
* reloptions, if set; otherwise, return NULL.
* Given a relation's pg_class tuple, return a palloc'd copy of the
* AutoVacOpts portion of reloptions, if set; otherwise, return NULL.
*
* Note: callers do not have a relation lock on the table at this point,
* so the table could have been dropped, and its catalog rows gone, after
@ -2868,6 +2885,7 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
autovac_table *tab = NULL;
bool wraparound;
AutoVacOpts *avopts;
bool free_avopts = false;
/* fetch the relation's relcache entry */
classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
@ -2880,8 +2898,10 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
* main table reloptions if the toast table itself doesn't have.
*/
avopts = extract_autovac_opts(classTup, pg_class_desc);
if (classForm->relkind == RELKIND_TOASTVALUE &&
avopts == NULL && table_toast_map != NULL)
if (avopts)
free_avopts = true;
else if (classForm->relkind == RELKIND_TOASTVALUE &&
table_toast_map != NULL)
{
av_relation *hentry;
bool found;
@ -2983,6 +3003,8 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
avopts->vacuum_cost_delay >= 0));
}
if (free_avopts)
pfree(avopts);
heap_freetuple(classTup);
return tab;
}
@ -3014,6 +3036,10 @@ recheck_relation_needs_vacanalyze(Oid relid,
effective_multixact_freeze_max_age,
dovacuum, doanalyze, wraparound);
/* Release tabentry to avoid leakage */
if (tabentry)
pfree(tabentry);
/* ignore ANALYZE for toast tables */
if (classForm->relkind == RELKIND_TOASTVALUE)
*doanalyze = false;
@ -3236,19 +3262,23 @@ autovacuum_do_vac_analyze(autovac_table *tab, BufferAccessStrategy bstrategy)
VacuumRelation *rel;
List *rel_list;
MemoryContext vac_context;
MemoryContext old_context;
/* Let pgstat know what we're doing */
autovac_report_activity(tab);
/* Set up one VacuumRelation target, identified by OID, for vacuum() */
rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
rel_list = list_make1(rel);
/* Create a context that vacuum() can use as cross-transaction storage */
vac_context = AllocSetContextCreate(CurrentMemoryContext,
"Vacuum",
ALLOCSET_DEFAULT_SIZES);
/* Set up one VacuumRelation target, identified by OID, for vacuum() */
old_context = MemoryContextSwitchTo(vac_context);
rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
rel_list = list_make1(rel);
MemoryContextSwitchTo(old_context);
vacuum(rel_list, &tab->at_params, bstrategy, vac_context, true);
MemoryContextDelete(vac_context);