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Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Autovacuum seems to block database: WARNING worker took too long
	to start
From: Alvaro Herrera <alvherre@commandprompt.com>
To: =?utf-8?q?Pablo_Delgado_D=C3=ADaz-Pache?= <delgadop@gmail.com>
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Date: Tue, 16 Nov 2010 16:09:34 -0300
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Excerpts from Pablo Delgado Díaz-Pache's message of mar nov 16 12:18:09 -0300 2010:
> Not sure what you mean.
> 
> Once we start getting that error in the postgres log, there is no autovacuum
> entry. Only that error message once every minute (and as i wrote in my last
> email, the same message all the time).

Yeah.  This means that the autovacuum launcher daemon is still running
and trying to schedule new jobs, but it's not able to for some reason.
When it tries to start a new one, it sees the old one still waiting to
start running; and then it logs this message.

To start a new job, what it does is send a signal to postmaster and wait
for it to create a child process.  This is the part that's not working.

> The question is what is causing postgres to stop working. Autovacuum or
> another reason? If it's another reason ... what could it be?

I have no idea what's going on.  I have never seen this problem.  If you
see it happen again, please get a stacktrace from postmaster; and/or
strace it.

-- 
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
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