[Pgpool-general] Unable to accept new connection after terminating pgpool backend process

[Tatsuo Ishii]

Then it must be a bug, or at least an unexpected feature.
I will look into this.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> It does trigger a failover and worse, once a backend has been
> terminated with SIGINT, no new connections can be established through
> the pool until the whole pool is restarted.  That's exactly the
> problem we are trying to solve.
> 
> -K
> 
> On Sun, Jan 2, 2011 at 3:54 AM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>>> On Wed, Dec 29, 2010 at 7:41 AM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>>>>>>> What we like to have is the ability to:
>>>>>>> - Treat the error code got back from pg_terminate_backend (or the kill
>>>>>>> command) as a regular disconnect
>>>>>>
>>>>>> It isn't possible without changing PostgreSQL itself.
>>>>>
>>>>> Can you please explain why?  If we kill -INT a backend postgres
>>>>> process, it doesn't take the whole database cluster down, it shouldn't
>>>>> take the whole pool down either.  The fact that it does is a bug in
>>>>> pg_pool IMO.
>>>>
>>>> The problem is PostgreSQL returns exactly the same error code when
>>>> postmaster goes down. See:
>>>>
>>>> http://archives.postgresql.org/pgsql-hackers/2010-05/msg00629.php
>>>>
>>>
>>> OK, I'm not familiar enough with postgres code to understand why
>>> killing a single backend should return the same code to client as a
>>> controlled shutdown of the database.  However, if the DB is shutdown,
>>> *every* pool process will get the error code, in our case only the one
>>> running the query that needed to be stopped.
>>>
>>> Since ADMIN_SHUTDOWN_ERROR_CODE is sent by the backend for two
>>> completely different events, perhaps the answer is to not test for it.
>>>  If a single backend goes down you send the error code to the client
>>> and disconnect.  If all backends go down, that's effectively the same
>>> as the database machine crashing.
>>
>> If the particular use is canceling the long running query, why don't
>> you use query cancel? It can be done by signaling PostgreSQL backend
>> process with SIGINT signal. This does not trigger failover of
>> pgpool-II of course.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>>