Re: BUG #15804: Assertion failure when using logging_collector with EXEC_BACKEND

Michael Paquier <michael(at)paquier(dot)xyz> writes:
> On Thu, May 16, 2019 at 12:56:17PM +0900, Michael Paquier wrote:
>> The test is able to pass, but we have a race condition between the
>> moment the backend file gets saved and the moment we allow it to be
>> read. I have not spent much time checking the stack between
>> InitializeMaxBackends() and RemovePgTempFiles() in postmaster.c, but
>> 57431a9 triggers the failure.

> Oh, I think I got it. The issue is that we call RemovePgTempFiles()
> after starting the syslogger. This cannot be run with other processes
> running in parallel, and with EXEC_BACKEND there is the extra case
> where we have a pgsql_tmp/ at the root of the data folder, so the
> syslogger complains on that. By making RemovePgTempFiles() happen
> before starting the syslogger, then the test complains again about the
> assertion without my previous patch applied of course. With the patch
> applied, I get no complains.

Hm, should we separate the cleanup of the root pgsql_tmp/ from the rest of
what RemovePgTempFiles does? I'm still feeling like we should be trying
to launch the syslogger as soon as possible.

regards, tom lane