Re: BUG #15727: PANIC: cannot abort transaction 295144144, it was already committed

Hi,

On 2019-04-02 11:51:38 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2019-04-02 11:44:26 -0400, Tom Lane wrote:
> >> What that seems to indicate is that the "unexpected table_lock_tuple
> >> status" error was thrown during commit, which seems pretty odd.
>
> > I suspect that's a deferred trigger. But that code obviously could throw
> > errors, so we gotta handle that correctly.
>
> Deferred triggers execute before the real transaction commit, not during
> the critical section surrounding where we set the bit in pg_clog.
> But this error is seemingly getting thrown from within that critical
> section, otherwise we wouldn't have inconsistent xact status afterwards.

I don't think it was thrown during the critical section - we'd otherwise
see the ERROR about unexpected lock status converted to a PANIC (and the
"cannot abort transaction, already committed" is a PANIC itself). I
suspect it's more likely that we corrupt the xact.c status somewhere -
but it's hard to say without knowing more about the workload.

Greetings,

Andres Freund