If RegisterBackgroundWorker() (the non-dynamic kind that is only
loadable from shared_preload_libraries) fails to register the worker, it
writes a log message and proceeds, ignoring the registration request. I
think that is a mistake, it should be a hard error. The only way in
practice to fix the problem is to change shared_preload_libraries or
max_worker_processes, both requiring a restart anyway, so proceeding
without the worker is not useful.
Perhaps this kind of worker has not been widely used in practice, but we
now have the logical replication launcher registering that way, and the
auto-prewarm patch also proposes to add one. If you run out of worker
slots before the launcher is supposed to start, it just logs a message
and doesn't start. That seems prone to confuse.
Attached is a proposed patch (0002) to change the log level to ERROR.
The other patch (0001) gives some additional error context for the
log/error message that you get.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From 38c89ce84e5e4eadf88f432ee0c416121a5fc33b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Tue, 14 Feb 2017 10:39:06 -0500
Subject: [PATCH 1/3] Add errcontext to background worker registration
---
src/backend/postmaster/bgworker.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index cd99b0b392..db25a7f68b 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -824,7 +824,8 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
"Up to %d background workers can be registered with the current settings.",
max_worker_processes,
max_worker_processes),
- errhint("Consider increasing the configuration parameter \"max_worker_processes\".")));
+ errhint("Consider increasing the configuration parameter \"max_worker_processes\"."),
+ errcontext("registration of background worker \"%s\"", worker->bgw_name)));
return;
}
--
2.11.1
From 6d2f6ec75f160dce622d77ac55bc50858c337527 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Tue, 14 Feb 2017 10:39:51 -0500
Subject: [PATCH 2/3] Change failures in RegisterBackgroundWorker() to hard
errors
Previously, just a log message was written and the background worker
registration was ignored.
---
src/backend/postmaster/bgworker.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index db25a7f68b..a42bd0f758 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -790,19 +790,19 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
if (!process_shared_preload_libraries_in_progress && !internal)
{
if (!IsUnderPostmaster)
- ereport(LOG,
+ ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("background worker \"%s\": must be registered in shared_preload_libraries",
worker->bgw_name)));
return;
}
- if (!SanityCheckBackgroundWorker(worker, LOG))
+ if (!SanityCheckBackgroundWorker(worker, ERROR))
return;
if (worker->bgw_notify_pid != 0)
{
- ereport(LOG,
+ ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("background worker \"%s\": only dynamic background workers can request notification",
worker->bgw_name)));
@@ -817,7 +817,7 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
*/
if (++numworkers > max_worker_processes)
{
- ereport(LOG,
+ ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("too many background workers"),
errdetail_plural("Up to %d background worker can be registered with the current settings.",
@@ -835,7 +835,7 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
rw = malloc(sizeof(RegisteredBgWorker));
if (rw == NULL)
{
- ereport(LOG,
+ ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
return;
--
2.11.1
--
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