Re: EINTR while resizing dsm segment.

The only change we made on the disk, is the encryption at OS level.
Not sure this can be something related.

Il giorno mar 7 apr 2020 alle ore 10:58 Nicola Contu <nicola(dot)contu(at)gmail(dot)com>
ha scritto:

> So that seems to be a bug, correct?
> Just to confirm, I am not using NFS, it is directly on disk.
>
> Other than that, is there a particular option we can set in the
> postgres.conf to mitigate the issue?
>
> Thanks a lot for your help.
>
>
> Il giorno sab 4 apr 2020 alle ore 02:49 Thomas Munro <
> thomas(dot)munro(at)gmail(dot)com> ha scritto:
>
>> On Thu, Apr 2, 2020 at 9:25 PM Kyotaro Horiguchi
>> <horikyota(dot)ntt(at)gmail(dot)com> wrote:
>> > I provided the subject, and added -hackers.
>> >
>> > > Hello,
>> > > I am running postgres 11.5 and we were having issues with shared
>> segments.
>> > > So I increased the max_connection as suggested by you guys and
>> reduced my
>> > > work_mem to 600M.
>> > >
>> > > Right now instead, it is the second time I see this error :
>> > >
>> > > ERROR: could not resize shared memory segment
>> "/PostgreSQL.2137675995" to
>> > > 33624064 bytes: Interrupted system call
>> >
>> > The function posix_fallocate is protected against EINTR.
>> >
>> > | do
>> > | {
>> > | rc = posix_fallocate(fd, 0, size);
>> > | } while (rc == EINTR && !(ProcDiePending || QueryCancelPending));
>> >
>> > But not for ftruncate and write. Don't we need to protect them from
>> > ENTRI as the attached?
>>
>> We don't handle EINTR for write() generally because that's not
>> supposed to be necessary on local files (local disks are not "slow
>> devices", and we document that if you're using something like NFS you
>> should use its "hard" mount option so that it behaves that way too).
>> As for ftruncate(), you'd think it'd be similar, and I can't think of
>> a more local filesystem than tmpfs (where POSIX shmem lives on Linux),
>> but I can't seem to figure that out from reading man pages; maybe I'm
>> reading the wrong ones. Perhaps in low memory situations, an I/O wait
>> path reached by ftruncate() can return EINTR here rather than entering
>> D state (non-interruptable sleep) or restarting due to our SA_RESTART
>> flag... anyone know?
>>
>> Another thought: is there some way for the posix_fallocate() retry
>> loop to exit because (ProcDiePending || QueryCancelPending), but then
>> for CHECK_FOR_INTERRUPTS() to do nothing, so that we fall through to
>> reporting the EINTR?
>>
>