From c758119e5bfb47b38cf957f9a5a37ceae96fa9b3 Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Mon, 6 Jan 2025 15:01:22 -0600 Subject: Allow changing autovacuum_max_workers without restarting. This commit introduces a new parameter named autovacuum_worker_slots that controls how many autovacuum worker slots to reserve during server startup. Modifying this new parameter's value does require a server restart, but it should typically be set to the upper bound of what you might realistically need to set autovacuum_max_workers. With that new parameter in place, autovacuum_max_workers can now be changed with a SIGHUP (e.g., pg_ctl reload). If autovacuum_max_workers is set higher than autovacuum_worker_slots, a WARNING is emitted, and the server will only start up to autovacuum_worker_slots workers at a given time. If autovacuum_max_workers is set to a value less than the number of currently-running autovacuum workers, the existing workers will continue running, but no new workers will be started until the number of running autovacuum workers drops below autovacuum_max_workers. Reviewed-by: Sami Imseih, Justin Pryzby, Robert Haas, Andres Freund, Yogesh Sharma Discussion: https://postgr.es/m/20240410212344.GA1824549%40nathanxps13 --- src/backend/storage/lmgr/proc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/backend/storage/lmgr/proc.c') diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index c7a972df7dd..49204f91a20 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -150,7 +150,7 @@ ProcGlobalSemas(void) * So, now we grab enough semaphores to support the desired max number * of backends immediately at initialization --- if the sysadmin has set * MaxConnections, max_worker_processes, max_wal_senders, or - * autovacuum_max_workers higher than his kernel will support, he'll + * autovacuum_worker_slots higher than his kernel will support, he'll * find out sooner rather than later. * * Another reason for creating semaphores here is that the semaphore @@ -284,13 +284,13 @@ InitProcGlobal(void) dlist_push_tail(&ProcGlobal->freeProcs, &proc->links); proc->procgloballist = &ProcGlobal->freeProcs; } - else if (i < MaxConnections + autovacuum_max_workers + NUM_SPECIAL_WORKER_PROCS) + else if (i < MaxConnections + autovacuum_worker_slots + NUM_SPECIAL_WORKER_PROCS) { /* PGPROC for AV or special worker, add to autovacFreeProcs list */ dlist_push_tail(&ProcGlobal->autovacFreeProcs, &proc->links); proc->procgloballist = &ProcGlobal->autovacFreeProcs; } - else if (i < MaxConnections + autovacuum_max_workers + NUM_SPECIAL_WORKER_PROCS + max_worker_processes) + else if (i < MaxConnections + autovacuum_worker_slots + NUM_SPECIAL_WORKER_PROCS + max_worker_processes) { /* PGPROC for bgworker, add to bgworkerFreeProcs list */ dlist_push_tail(&ProcGlobal->bgworkerFreeProcs, &proc->links); -- cgit v1.2.3