Thread: Addition of %b/backend_type in log_line_prefix of TAP test logs

Hi all,

While navigating through the logs in the CI, the buildfarm, or even my
own machine, I've found myself spending a lot of time looking at
very specific log entries to find out the PID of a specific process,
sometimes mistaking a normal backend vs a logical WAL sender while
looking for a PID, or just looking for an auxiliary process.

I'd like to suggest the following change in Cluster.pm:
-   print $conf "log_line_prefix = '%m [%p] %q%a '\n";
+   print $conf "log_line_prefix = '%m [%b,%p] %q%a '\n";

It is then possible to match a backend_type with a PID.  That
increases the quantity of the logs, of course, but I'm finding that
really helpful to have.  But perhaps it's only me?

Thanks,
--
Michael

On Wed, May 21, 2025 at 8:51 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> Hi all,
>
> While navigating through the logs in the CI, the buildfarm, or even my
> own machine, I've found myself spending a lot of time looking at
> very specific log entries to find out the PID of a specific process,
> sometimes mistaking a normal backend vs a logical WAL sender while
> looking for a PID, or just looking for an auxiliary process.
>
> I'd like to suggest the following change in Cluster.pm:
> -   print $conf "log_line_prefix = '%m [%p] %q%a '\n";
> +   print $conf "log_line_prefix = '%m [%b,%p] %q%a '\n";

+1 to this change.

Since pg_regress uses log_line_prefix = '%m %b[%p] %q%a ',
isn't it better to use the same setting in TAP tests as well?

Regards,

--
Fujii Masao

> On 21 May 2025, at 04:48, Michael Paquier <michael@paquier.xyz> wrote:
> 
> On Wed, May 21, 2025 at 11:41:18AM +0900, Fujii Masao wrote:
>> Since pg_regress uses log_line_prefix = '%m %b[%p] %q%a ',
>> isn't it better to use the same setting in TAP tests as well?
> 
> Oh, right, good point.  I've managed to miss this part in
> pg_regress.c.  Using the same value makes even more sense.

Agreed, and +1 on the change in general.

--
Daniel Gustafsson

Michael Paquier <michael@paquier.xyz> writes:
> On Wed, May 21, 2025 at 09:24:26AM +0200, Daniel Gustafsson wrote:
>> Agreed, and +1 on the change in general.

> Another point perhaps worth considering after a second look: how about
> pg_ci_base.conf?  We have the following line there, exposing this
> configuration with TEMP_CONFIG:
> src/tools/ci/pg_ci_base.conf:log_line_prefix = '%m [%p][%b] %q[%a][%v:%x] '

> The two other ones are:
> src/test/perl/PostgreSQL/Test/Cluster.pm: '%m [%p] %q%a '
> src/test/regress/pg_regress.c: '%m %b[%p] %q%a '

> Perhaps it would be better to apply the same configuration as the CI
> by default at the end?

I'd vote for standardizing on pg_regress.c's spelling, as that's got
the most usage history behind it.  I'm unexcited about bloating the
logs with [%v:%x] --- that's data I've very seldom needed.

            regards, tom lane