PostgreSQL Bugs - pg_ctl inappropriately timing out?

Author

pg_ctl inappropriately timing out?

Josh Berkus

2005-06-07, 8:24 pm

Folks:

Issue: pg_ctl seems to be prematurely timing out.
Version: 8.0.3
Severity: Annoying
Description:
1. Do an immense load on a database, like 2.5gb.
2. Right after the COPY finishes, send a pg_ctl -m fast stop to the server.
3. You will get:
pg_ctl: postmaster does not shut down

What Seems To Be Happening:
When you call pg_ctl --stop, the WAL is still writing out to the database
and postmaster won't shut down until it's done, which can take a couple
minutes. In the meantime, pg_ctl is timing out and prematurely reporting
failure.

Resolution:
Not sure, really. Is there some way for pg_ctl to intelligently detect
this situation? To set a timeout value for pg_ctl via a command-line
option?

--
--Josh

Josh Berkus
Aglio Database Solutions
San Francisco

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Alvaro Herrera

2005-06-07, 8:24 pm

On Tue, Jun 07, 2005 at 04:16:49PM -0700, Josh Berkus wrote:
> Folks:
>
> Issue: pg_ctl seems to be prematurely timing out.
> Version: 8.0.3
> Severity: Annoying
> Description:
> 1. Do an immense load on a database, like 2.5gb.
> 2. Right after the COPY finishes, send a pg_ctl -m fast stop to the server.
> 3. You will get:
> pg_ctl: postmaster does not shut down
>
> What Seems To Be Happening:
> When you call pg_ctl --stop, the WAL is still writing out to the database
> and postmaster won't shut down until it's done, which can take a couple
> minutes. In the meantime, pg_ctl is timing out and prematurely reporting
> failure.
>
> Resolution:
> Not sure, really. Is there some way for pg_ctl to intelligently detect
> this situation? To set a timeout value for pg_ctl via a command-line
> option?

Is there any way for pg_ctl to detect a "server is shutting down"
message? Not sure what it'd do with it though ...

--
Alvaro Herrera (<alvherre[a]surnet.cl> )
"Escucha y olvidarás; ve y recordarás; haz y entenderás" (Confucio)

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Tom Lane

2005-06-08, 3:24 am

Alvaro Herrera <alvherre@surnet.cl> writes:
> On Tue, Jun 07, 2005 at 04:16:49PM -0700, Josh Berkus wrote:
[color=darkred]
> Is there any way for pg_ctl to detect a "server is shutting down"
> message? Not sure what it'd do with it though ...

It strikes me that the server shouldn't ever get a couple minutes behind
on writing dirty buffers; this seems more like a bgwriter configuration
issue than pg_ctl's fault. Consider that in a standard Unix
configuration you will get about 20 seconds between SIGTERM and SIGKILL
when init wants to shut you down ...

regards, tom lane

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Josh Berkus

2005-06-08, 11:24 am

Tom,

> It strikes me that the server shouldn't ever get a couple minutes behind
> on writing dirty buffers; this seems more like a bgwriter configuration
> issue than pg_ctl's fault. Consider that in a standard Unix
> configuration you will get about 20 seconds between SIGTERM and SIGKILL
> when init wants to shut you down ...

Well, I can run an actual timer if you like. But it's definitely more than
20 seconds. And we're using the default bgwriter config, perhaps I should
set it to 0?

--
Josh Berkus
Aglio Database Solutions
San Francisco

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