On 2021-03-07 19:16, Bharath Rupireddy wrote:
On Fri, Feb 5, 2021 at 5:15 PM Bharath Rupireddy
<bharath.rupireddyforpostg...@gmail.com> wrote:
pg_terminate_backend and pg_cancel_backend with postmaster PID produce
"PID XXXX is not a PostgresSQL server process" warning [1], which
basically implies that the postmaster is not a PostgreSQL process at
all. This is a bit misleading because the postmaster is the parent of
all PostgreSQL processes. Should we improve the warning message if the
given PID is postmasters' PID?
+1. I felt it was a bit confusing when reviewing a thread[1].
If yes, how about a generic message for both of the functions -
"signalling postmaster process is not allowed" or "cannot signal
postmaster process" or some other better suggestion?
[1] 2471176 ---> is postmaster PID.
postgres=# select pg_terminate_backend(2471176);
WARNING: PID 2471176 is not a PostgreSQL server process
pg_terminate_backend
----------------------
f
(1 row)
postgres=# select pg_cancel_backend(2471176);
WARNING: PID 2471176 is not a PostgreSQL server process
pg_cancel_backend
-------------------
f
(1 row)
I'm attaching a small patch that emits a warning "signalling
postmaster with PID %d is not allowed" for postmaster and "signalling
PostgreSQL server process with PID %d is not allowed" for auxiliary
processes such as checkpointer, background writer, walwriter.
However, for stats collector and sys logger processes, we still get
"PID XXXXX is not a PostgreSQL server process" warning because they
don't have PGPROC entries(??). So BackendPidGetProc and
AuxiliaryPidGetProc will not help and even pg_stat_activity is not
having these processes' pid.
I also ran into the same problem while creating a patch in [2].
I'm now wondering if changing the message to something like
"PID XXXX is not a PostgreSQL backend process".
"backend process' is now defined as "Process of an instance
which acts on behalf of a client session and handles its
requests." in Appendix.
[1]
https://www.postgresql.org/message-id/CALDaNm3ZzmFS-%3Dr7oDUzj7y7BgQv%2BN06Kqyft6C3xZDoKnk_6w%40mail.gmail.com
[2]
https://www.postgresql.org/message-id/0271f440ac77f2a4180e0e56ebd944d1%40oss.nttdata.com
Regards,
--
Atsushi Torikoshi
NTT DATA CORPORATION
