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Add two attributes to pg_stat_database for parallel workers activity

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Two attributes are added to pg_stat_database:
* parallel_workers_to_launch, counting the total number of parallel
workers that were planned to be launched.
* parallel_workers_launched, counting the total number of parallel
workers actually launched.

The ratio of both fields can provide hints that there are not enough
slots available when launching parallel workers, also useful when
pg_stat_statements is not deployed on an instance (i.e. cf54a2c002).

This commit relies on de3a2ea3b2, that has added two fields to EState,
that get incremented when executing Gather or GatherMerge nodes.

A test is added in select_parallel, where parallel workers are spawned.

Bump catalog version.

Author: Benoit Lobréau
Discussion: https://postgr.es/m/783bc7f7-659a-42fa-99dd-ee0565644e25@dalibo.com
This commit is contained in:
Michael Paquier
2024-11-11 10:40:48 +09:00
parent bf8835ea97
commit e7a9496de9
11 changed files with 108 additions and 1 deletions
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19
src/backend/utils/activity/pgstat_database.c
View File

@@ -262,6 +262,23 @@ AtEOXact_PgStat_Database(bool isCommit, bool parallel)
}
}
/*
* Notify the stats system about parallel worker information.
*/
void
pgstat_update_parallel_workers_stats(PgStat_Counter workers_to_launch,
PgStat_Counter workers_launched)
{
PgStat_StatDBEntry *dbentry;
if (!OidIsValid(MyDatabaseId))
return;
dbentry = pgstat_prep_database_pending(MyDatabaseId);
dbentry->parallel_workers_to_launch += workers_to_launch;
dbentry->parallel_workers_launched += workers_launched;
}
/*
* Subroutine for pgstat_report_stat(): Handle xact commit/rollback and I/O
* timings.
@@ -425,6 +442,8 @@ pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
PGSTAT_ACCUM_DBCOUNT(sessions_abandoned);
PGSTAT_ACCUM_DBCOUNT(sessions_fatal);
PGSTAT_ACCUM_DBCOUNT(sessions_killed);
PGSTAT_ACCUM_DBCOUNT(parallel_workers_to_launch);
PGSTAT_ACCUM_DBCOUNT(parallel_workers_launched);
#undef PGSTAT_ACCUM_DBCOUNT
pgstat_unlock_entry(entry_ref);

6
src/backend/utils/adt/pgstatfuncs.c
View File

@@ -1039,6 +1039,12 @@ PG_STAT_GET_DBENTRY_INT64(sessions_fatal)
/* pg_stat_get_db_sessions_killed */
PG_STAT_GET_DBENTRY_INT64(sessions_killed)
/* pg_stat_get_db_parallel_workers_to_launch */
PG_STAT_GET_DBENTRY_INT64(parallel_workers_to_launch)
/* pg_stat_get_db_parallel_workers_launched */
PG_STAT_GET_DBENTRY_INT64(parallel_workers_launched)
/* pg_stat_get_db_temp_bytes */
PG_STAT_GET_DBENTRY_INT64(temp_bytes)