Hi all, When lacking connection slots, the backend returns a simple "sorry, too many clients", which is something that has been tweaked by recent commit ea92368 for WAL senders. However, the same message would show up for autovacuum workers and bgworkers. Based on the way autovacuum workers are spawned by the launcher, and the way bgworkers are added, it seems that this cannot actually happen. Still, in my opinion, providing more context can be helpful for people trying to work on features related to such code so as they can get more information than what would normally happen for normal backends.
I am wondering as well if this could not help for issues like this one, which has popped out today and makes me wonder if we don't have race conditions with the way dynamic bgworkers are spawned: https://www.postgresql.org/message-id/CAONUJSM5X259vAnnwSpqu=vnrecfgsj-cgrhys4p5yyrvwk...@mail.gmail.com There are four code paths which report the original "sorry, too many clients", and the one of the patch attached can easily track the type of connection slot used which helps for better context messages when a process is initialized. Would that be helpful for at least debugging purposes? Thanks, -- Michael
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 0da5b19719..418363000b 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -349,15 +349,25 @@ InitProcess(void)
/*
* If we reach here, all the PGPROCs are in use. This is one of the
* possible places to detect "too many backends", so give the standard
- * error message. XXX do we need to give a different failure message
- * in the autovacuum case?
+ * error message.
*/
SpinLockRelease(ProcStructLock);
- if (am_walsender)
+ if (IsAnyAutoVacuumProcess())
+ ereport(FATAL,
+ (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
+ errmsg("number of requested autovacuum workers exceeds autovacuum_max_workers (currently %d)",
+ autovacuum_max_workers)));
+ else if (IsBackgroundWorker)
+ ereport(FATAL,
+ (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
+ errmsg("number of requested worker processes exceeds max_worker_processes (currently %d)",
+ max_worker_processes)));
+ else if (am_walsender)
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("number of requested standby connections exceeds max_wal_senders (currently %d)",
max_wal_senders)));
+
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("sorry, too many clients already")));
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