[pgpool-general: 2646] Re: pcp_recovery_node failing in stage 1

[Tatsuo Ishii]

Ridiculous. There's no code in pgpool which sends signal 2 to recovery
command. Is it possible to start pgpool from strace and do the
recovery so that we could find who sends the signal?

strace -f pgpool start

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

> The stage 1 script is not careful with exit codes, so it continues
> after the failed rsync and eventually exits with success.  This tricks
> pgpool into continuing with stage 2, but it's definitely the state 1
> command that is failing.
> 
> Sean
> 
> On 14-03-21 06:20 AM, Tatsuo Ishii wrote:
>>> Sorry, the subject line should have said stage *1*.
>> Really? From what I read from pgpool log:
>>
>> 2014-03-20 12:42:43 LOG:   pid 18259: 1st stage is done
>> 2014-03-20 12:42:43 LOG:   pid 18259: starting 2nd stage
>> 2014-03-20 12:42:47 LOG:   pid 18259: CHECKPOINT in the 2nd stage done
>> 2014-03-20 12:42:47 LOG: pid 18259: starting recovery command: "SELECT
>> pgpool_recovery('pgpool_recovery_pitr.sh', 'psql02.compusult.net',
>> '/var/lib/pgsql/9.2/data')"
>> 2014-03-20 12:42:49 LOG: pid 18259: check_postmaster_started: try to
>> connect to postmaster on hostname:psql02.compusult.net
>> database:postgres user:postgres (retry 0 times)
>>
>> I saw "1st stage is done" and I guess the first stage has been
>> succeeded but the second stage failed. What does the second stage look
>> like?
>>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>>
>>> On 14-03-20 12:48 PM, Sean Hogan wrote:
>>>> Hi,
>>>>
>>>> In my setup at the moment I have a pair of version 3.3.2 pgpool
>>>> instances with two backend PostgreSQL 9.2.4 servers, all running on
>>>> CentOS 6.4.  The PostgreSQL data directories are quite large - 144GB.
>>>> I have run into a situation where pcp_recovery_node consistently fails
>>>> with a BackendError.
>>>>
>>>> The stage 1 recovery command is a script called do-base-backup.sh that
>>>> runs an rsync as follows:
>>>>
>>>>      rsync -Cacvv --delete \
>>>>              --exclude postmaster.pid --exclude postmaster.opts \
>>>>              --exclude recovery.done \
>>>>              --exclude pg_log/\* --exclude pg_xlog/\* \
>>>>              $SOURCE/ $DESTINATION/ 2>&1 |
>>>>      mailx -s "rsync verbose output" sean at compusult.net
>>>>
>>>> For some reason this rsync is failing after some minutes (typically 10
>>>> to 12) with undocumented exit code 255.  The verbose rsync logging
>>>> says this:
>>>>
>>>>      Killed by signal 2.
>>>>      rsync: writefd_unbuffered failed to write 4 bytes to socket [sender]:
>>>>      Broken pipe (32)
>>>>      rsync: connection unexpectedly closed (50735 bytes received so far)
>>>>      [sender]
>>>>      rsync error: unexplained error (code 255) at io.c(600) [sender=3.0.6]
>>>>
>>>> Googling has not brought up anything helpful other than bugs with
>>>> large files in older versions of rsync.  I'm fairly certain that is
>>>> not the case here, especially because of the "Killed by signal 2",
>>>> which is suggestive of some sort of timeout on the pgpool end.
>>>>
>>>> The specific command line I'm using to recover the second database
>>>> node is:
>>>>
>>>>      sudo -u postgres /usr/local/bin/pcp_recovery_node 10000 psql01 9898
>>>>      postgres XXXXXX 1
>>>>
>>>> With such a large timeout value I shouldn't be hitting a timeout
>>>> there.
>>>>
>>>> The weird thing, which makes me point the finger at either pgpool or
>>>> pcp_recovery_node, is that if I run do-base-backup.sh manually it
>>>> works fine (and takes much much longer, as expected).
>>>>
>>>> Does pgpool have some internal limit on how long it will wait for the
>>>> 1st stage command to run?  I've attached the log file but it isn't
>>>> very informative.  (Note that the do-base-backup.sh script isn't
>>>> communicating the rsync failure back to pgpool, so pgpool goes ahead
>>>> and runs stage 2.  Of course, that fails because not everything has
>>>> been synced.)
>>>>
>>>> Thanks,
>>>> Sean
>>>>
>>>>
>>>> _______________________________________________
>>>> pgpool-general mailing list
>>>> pgpool-general at pgpool.net
>>>> http://www.pgpool.net/mailman/listinfo/pgpool-general
>