Re: replication_timeout not effective

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...

> Blocking in send(2) might could occur for async-rep connection but not
> likely for sync-rep since it does not fill the buffers of libpq and
> socket easilly.

You just need larger transactions for it. A COPY or so ought to do it.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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