Re: PostgreSQL doesn't stop propley when --slot option is specified with pg_receivexlog.

On 2014-11-15 03:25:16 +0900, Fujii Masao wrote:
> On Fri, Nov 14, 2014 at 7:22 PM, <furuyao(at)pm(dot)nttdata(dot)co(dot)jp> wrote:
> > Hi,
> >
> > "pg_ctl stop" does't work propley, if --slot option is specified when WAL is flushed only it has switched.
> > These processes still continue even after the posmaster failed:pg_receivexlog, walsender and logger.
>
> I could reproduce this problem. At normal shutdown, walsender keeps waiting
> for the last WAL record to be replicated and flushed in pg_receivexlog. But
> pg_receivexlog issues sync command only when WAL file is switched. Thus,
> since pg_receivexlog may never flush the last WAL record, walsender may have
> to keep waiting infinitely.

Right.

> pg_recvlogical handles this problem by calling fsync() when it receives the
> request of immediate reply from the server. That is, at shutdown, walsender
> sends the request, pg_receivexlog receives it, flushes the last WAL record,
> and sends the flush location back to the server. Since walsender can see that
> the last WAL record is successfully flushed in pg_receivexlog, it can
> exit cleanly.
>
> One idea to the problem is to introduce the same logic as pg_recvlogical has,
> to pg_receivexlog. Thought?

Sounds sane to me. Are you looking into doing that?

Greetings,

Andres Freund

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