Re: PANIC: could not fsync file "pg_multixact/..." since commit dee663f7843

On Wed, Nov 04, 2020 at 02:49:24PM +1300, Thomas Munro wrote:
>On Wed, Nov 4, 2020 at 2:32 PM Tomas Vondra
><tomas.vondra@2ndquadrant.com> wrote:
>> After a while (~1h on my machine) the pg_multixact gets over 10GB, which
>> triggers a more aggressive cleanup (per MultiXactMemberFreezeThreshold).
>> My guess is that this discards some of the files, but checkpointer is
>> not aware of that, or something like that. Not sure.
>
>Urgh.  Thanks.  Looks like perhaps the problem is that I have
>RegisterSyncRequest(&tag, SYNC_FORGET_REQUEST, true) in one codepath
>that unlinks files, but not another.  Looking.

Maybe. I didn't have time to investigate this more deeply, and it takes
quite a bit of time to reproduce. I can try again with extra logging or
test some proposed fixes, if you give me a patch.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services