[pgpool-general: 4842] Re: failover_command and follow_command does not exit and hangs indefinitely

[Tatsuo Ishii]

> 02.08.2016 11:12, Tatsuo Ishii пишет:
>>> 02.08.2016 09:44, Tatsuo Ishii пишет:
>>>>> On 02.08.2016 4:26, Tatsuo Ishii wrote:
>>>>>>> I'm trying to configure expandable cluster using Ubuntu 14.04 LTS,
>>>>>>> PostgreSQL 9.5 and PgPool 3.5.3.
>>>>>>> I'm having a problem with failover/follow commands: any command, be
>>>>>>> that
>>>>>>> ansible-playbook, ssh or anything else does not exit after successful
>>>>>>> run and hangs indefinitely, reacting only to "kill -9".  Which, in
>>>>>>> case
>>>>>>> of failover script, makes pgpool running that command wait for it's
>>>>>>> exit
>>>>>>> and also to hang.
>>>>>>> My current workaround is forking script, running a command in the new
>>>>>>> fork, and terminate it after successful execution. Obviously, its not
>>>>>>> a
>>>>>>> viable production solution.
>>>>>>> Please help me undestand, why is this happening?
>>>>>> I guess your fail over script is waiting for stdin/stdout/stderr
>>>>>> closed?
>>>>> I dont exactly know, that's why i'm asking. Right now i'm having a
>>>>> problem with ansible-playbook and ssh.
>>>> Without seeing the fail over script, I can't tell. Can you share the
>>>> fail over script you created?
>>>>
>>> Yes, i'm attaching script to this message.
>> I'm not familiar with Python but I guess at leat you should redirect
>> stdin and stdout to /dev/null for this ssh. Pgpool-II executes fail
>> over command by using system(3).
>>
>>         promote_command = ssh + 'postgres@' + pgnodemaster + ' /usr/bin/repmgr standby promote'
>>
>>     follow_command = ssh + 'postgres@' + sys.argv[2] + ' /usr/bin/repmgr standby follow'
>>
>> To do that, see this page for example:
>>
>> http://stackoverflow.com/questions/1628204/how-to-run-a-command-in-background-using-ssh-and-detach-the-session
>>
> But then, how would i know that command has finished its run?

You can redirect stderr/stdout to a log file.

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