Re: BUG #18003: FATAL: cannot request additional shared memory outside shmem_request_hook

Hi,

On 2023-06-27 20:27:42 +0000, PG Bug reporting form wrote:
> Jun 27 23:21:18 hq-pgsql-test01 postmaster[1491680]: 2023-06-27 23:21:18.874
> EEST [1491680] LOG:  pgaudit extension initialized
> Jun 27 23:21:18 hq-pgsql-test01 postmaster[1491680]: 2023-06-27 23:21:18.876
> EEST [1491680] FATAL:  cannot request additional shared memory outside
> shmem_request_hook

pgaudit prints "pgaudit extension initialized" at the end of _PG_init():
https://github.com/pgaudit/pgaudit/blob/master/pgaudit.c#L2254

So it's likely not pgaudit.  What is shared_preload_libraries set to?

Unfortunately we only print library names after loading them, even at debug
level.  But we do print information while searching libraries if you change
log_min_messages to debug3.  Could you reproduce the issue with that and show
us the log messages?



That's not going to help you / the reporter, but to make issues like this
easier to debug in the future, I think we should

a) install an error context in load_libraries() printing the GUC name and
b) install an error context in internal_load_library() printing the name of
   the shared library name

The reason for doing both a) and b) is that a) makes it easier to figure out
the cause of the library being loaded and b) would also work when the library
is loaded for a different reason, e.g. due to executing a function residing in
the library.

A bit surprised that we don't have that already.

Greetings,

Andres Freund