Thread: BUG #17140: pg_try_advisory_xact_lock produces a WARNINIG on unsuccessful lock

The following bug has been logged on the website:

Bug reference:      17140
Logged by:          Yuri Cherio
Email address:      cherio@gmail.com
PostgreSQL version: 13.3
Operating system:   Ubuntu Linux 20.04
Description:

Function "pg_try_advisory_xact_lock" triggers a WARNING message when the
lock is already owned by someone else. The documentation explicitly mentions
warnings on advisory unlock functions and those are understandable - the
developer should not try to unlock what's not owned.

However the advisory lock functions are there for this specific reason -
test whether a resource is locked or not. A negative test should not produce
a WARNING.

PG Bug reporting form <noreply@postgresql.org> writes:
> Function "pg_try_advisory_xact_lock" triggers a WARNING message when the
> lock is already owned by someone else.

I failed to duplicate this behavior.  I did this in session A:

regression=# begin;
BEGIN
regression=*# select pg_try_advisory_xact_lock(1);
 pg_try_advisory_xact_lock 
---------------------------
 t
(1 row)

then this in session B:

regression=# select pg_try_advisory_xact_lock(1);
 pg_try_advisory_xact_lock 
---------------------------
 f
(1 row)

No warning...

            regards, tom lane