[pgpool-general: 8089] Re: Segfaults on PgPool-II 4.3.1

Tatsuo Ishii ishii at sraoss.co.jp
Wed Apr 20 11:35:03 JST 2022


As a side note:

The commit tried to fix the problem. However I was not able to
reproduce the problem and am not 100% sure the commit solves the
problem.

If you cannot build pgpool from the source code, you can wait until
May 19th, 2022. On the day we will release Pgpool-II 4.3.2, which
includes the commit.

Best reagards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> Hello,
> 
> Sorry for the late reply.
> We changed the way of shared memory access  where Seg fault orrured to a safer way.
> https://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=f1710d86b61de476372a0086b977647156af415c
> 
> If possible, could you please use the corrent V4_3_STABLE code to check the seg fault no
> longer occurs? 
> 
> Best regards.
> 
> On Thu, 14 Apr 2022 11:23:31 -0700
> Gautam Bellary <gautam at pulsasensors.com> wrote:
> 
>> Hi PgPool Team,
>> 
>> Is there any update on this?
>> Please let us know if there are any more details we can provide.
>> We continue to observe these segfaults regularly.
>> 
>> Thanks,
>> Gautam
>> 
>> On Wed, Apr 6, 2022 at 6:53 AM Bo Peng <pengbo at sraoss.co.jp> wrote:
>> 
>> > Hello,
>> >
>> > Thank you for reporting this issue.
>> >
>> > We are looking into this issue.
>> > We will let you know when we can figure out how to fix it.
>> >
>> > Regards,
>> >
>> > On Tue, 5 Apr 2022 10:16:09 -0700
>> > Gautam Bellary <gautam at pulsasensors.com> wrote:
>> >
>> > > Hello PgPool Team,
>> > >
>> > > We've been experiencing regular segfaults from PgPool-II 4.3.1 that
>> > appear
>> > > to have started recently after we began using this version. Our logs
>> > > include three different cases of segfaults, ("segfault at 14", "segfault
>> > at
>> > > 24" and "segfault at 0" in the logs) and we're seeing each segfault
>> > several
>> > > times a day on the master/leader instance in our production and test
>> > > clusters. While these segfaults do not always have an immediate impact on
>> > > connections between our servers and the database, we have observed an
>> > > increasing number of "bad connection" issues over time, which we did not
>> > > observe before upgrading to PgPool 4.3.1 and experiencing the segfaults.
>> > >
>> > > Details about our environment and the log lines for each segfault are
>> > > included below, and we've attached the core dump backtraces from gdb for
>> > > two of the three segfaults ("segfault at 14" and "segfault at 24"),
>> > > including `bt` and `bt full`. We'll add details for "segfault at 0" here
>> > or
>> > > in a new thread when we're able to capture a coredump for it.
>> > >
>> > > Thanks,
>> > > Gautam
>> > >
>> > > *Environment details (ubuntu-focal-20.04-amd64):*
>> > >
>> > >    - Cluster contains 3 PgPool nodes and 3 PSQL nodes, all on AWS EC2
>> > >    instances, pgpool.conf attached.
>> > >    - $ uname -a
>> > >    Linux ip-172-30-166-230 5.4.0-1038-aws #40-Ubuntu SMP Fri Feb 5
>> > 23:50:40
>> > >    UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
>> > >    - # SHOW POOL_VERSION;
>> > >         pool_version
>> > >    -----------------------
>> > >     4.3.1 (tamahomeboshi)
>> > >
>> > > *Log lines for segfaults:*
>> > > ISSUE 1 ("segfault at 14") - backtrace attached as
>> > > "segfault_at_14_backtrace_20220405.txt":
>> > > [350739.877169] pgpool[1157084]: segfault at 14 ip 000055b950530f25 sp
>> > > 00007ffc9e560f50 error 6 in pgpool[55b950503000+d9000]
>> > > [350739.877178] Code: 00 00 89 ef be 06 00 00 00 c7 44 24 50 01 00 00 00
>> > e8
>> > > ff 3e fd ff 85 c0 0f 88 a6 0f 00 00 89 ef e8 30 d0 03 00 48 8b 44 24 08
>> > > <c7> 40 14 00 00 00 00 4c 8d a4 24 20 01 00 00 48 8d 35 65 19 23 00
>> > >
>> > > ISSUE 2 ("segfault at 24") - backtrace attached as
>> > > "segfault_at_24_backtrace_20220405.txt":
>> > > [410790.718731] pgpool[1354761]: segfault at 24 ip 000055b9505308fa sp
>> > > 00007ffc9e560f50 error 6 in pgpool[55b950503000+d9000]
>> > > [410790.718740] Code: 80 78 4c 01 75 0a 83 78 50 00 0f 84 cd 05 00 00 31
>> > f6
>> > > 48 8d 3d 0d ac 0b 00 e8 72 c8 02 00 e8 7d 42 fd ff 89 c7 e8 d6 89 fd ff
>> > > <c7> 40 24 00 00 00 00 48 8b 05 38 89 1e 00 80 78 4c 01 0f 84 20 01
>> > >
>> > > ISSUE 3 ("segfault at 0") - backtrace unavailable at this time:
>> > > [ 4932.453010] pgpool[53241]: segfault at 0 ip 000055ae84d76163 sp
>> > > 00007ffd94e8c970 error 4 in pgpool[55ae84d2c000+d9000]
>> > > [ 4932.453018] Code: 01 c5 41 8b 45 10 85 c0 0f 8f f1 00 00 00 89 35 d3
>> > 60
>> > > 1e 00 48 8d 35 d0 60 1e 00 48 8d 7e fc 89 0d c6 60 1e 00 e8 4d bd ff ff
>> > > <8b> 38 4c 8d 68 18 83 ef 18 48 63 ff 48 89 3b e8 99 21 02 00 48 8b
>> >
>> >
>> > --
>> > Bo Peng <pengbo at sraoss.co.jp>
>> > SRA OSS, Inc. Japan
>> > http://www.sraoss.co.jp/
>> >
> 
> 
> -- 
> KAWAMOTO Masaya <kawamoto at sraoss.co.jp>
> SRA OSS, Inc. Japan
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