Re: replication_timeout not effective

2013/04/10 23:44、Andres Freund <andres(at)2ndquadrant(dot)com> のメッセージ:

> On 2013-04-10 23:37:44 +0900, Dang Minh Huong wrote:
>> Thanks all,
>>
>> (2013/04/10 22:55), Andres Freund wrote:
>>> On 2013-04-10 22:38:07 +0900, Kyotaro HORIGUCHI wrote:
>>>> Hello,
>>>>
>>>> On Wed, Apr 10, 2013 at 6:57 PM, Dang Minh Huong <kakalot49(at)gmail(dot)com> wrote:
>>>>> In 9.3, it sounds replication_timeout is replaced by wal_sender_timeout.
>>>>> So if it is solved in 9.3 i think there is a way to terminate it.
>>>>> I hope it is fixed in 9.1 soon
>>>> Hmm. He said that,
>>>>
>>>>> But in my environment the sender process is hang up (in several tens of minunites) if i turn off (by power off) Standby PC while *pg_basebackup* is excuting.
>>>> Does basebackup run only on 'replication connection' ?
>>>> As far as I saw base backup uses 'base backup' connection in addition
>>>> to 'streaming' connection. The former seems not under the control of
>>>> wal_sender_timeout or replication_timeout and easily blocked at
>>>> send(2) after sudden cut out of the network connection underneath.
>>>> Although the latter indeed is terminated by them.
>>> Yes, it's run via a walsender connection. The only "problem" is that it
>>> doesn't check for those timeouts. I am not sure it would be a good thing
>>> to do so to be honest. At least not using the same timeout as actual WAL
>>> sending, thats just has different characteristics.
>>> On the other hand, hanging around that long isn't nice either...
>> I tried max_wal_sender with 1, so when the walsender is hanging.
>> I can not run again pg_basebackup (or start the standby DB).
>> I'm increasing it to 2, so the seconds successfully. But i'm afraid
>> that when the third occures the hanging walsender in the first
>> is not yet terminated...
>>
>> I think not, but is there a way to terminate hanging up but not
>> restart PostgreSQL server or kill walsender process?
>> (kill walsender process can caused a crash to DB server,
>> so i don't want to do it).
>
> Depending on where its hanging a normal SELECT
> pg_terminate_backend(pid); might do it.
>
Greate! it worked. Thank you very much.

> Otherwise you will have to wait for the operating system's tcp timeout.
>
> Greetings,
>
> Andres Freund
>
> --
> Andres Freund http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services

Regards,
Huong DM