Re: Should we improve "PID XXXX is not a PostgreSQL server process" warning for pg_terminate_backend(<<postmaster_pid>>)?

On Thu, Nov 18, 2021 at 5:01 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
> The following is what I made up in my mind after looking at other
> existing messages, like [1] and the review comments:
> errmsg("cannot send signal to postmaster %d", pid,   --> the process
> is postmaster but the caller isn't allowed to signal.
> errmsg("cannot send signal to PostgreSQL server process %d", pid,
> --> the process is a postgresql process but the caller isn't allowed
> to signal.
> errmsg("PID %d is not a PostgreSQL backend process", pid,  ---> it may
> be another postgres processes like syslogger or stats collector or
> non-postgres process but not a backend process.
>
> Thoughts?
>
> [1]
> (errmsg("could not send signal to process %d: %m", pid)));
> (errmsg("failed to send signal to postmaster: %m")));

Here's the v4 patch with the above changes, the output looks like [1].
Please review it further.

[1]
postgres=# select pg_terminate_backend(2407245);
WARNING:  cannot send signal to postmaster 2407245
 pg_terminate_backend
----------------------
 f
(1 row)

postgres=# select pg_terminate_backend(2407246);
WARNING:  cannot send signal to PostgreSQL server process 2407246
 pg_terminate_backend
----------------------
 f
(1 row)

postgres=# select pg_terminate_backend(2407286);
WARNING:  PID 2407286 is not a PostgreSQL backend process
 pg_terminate_backend
----------------------
 f
(1 row)

Regards,
Bharath Rupireddy.