Date: Fri, 31 Jul 2009 19:49:02 -0400
From: Alvaro Herrera <alvherre@commandprompt.com>
To: Luke Koops <luke.koops@entrust.com>
Cc: pgsql-bugs@postgresql.org
Subject: Re: BUG #4958: Stats collector hung on
	WaitForMultipleObjectsEx while attempting to recv a datagram
Message-ID: <20090731234901.GD11098@alvh.no-ip.org>
References: <200907311459.n6VExuSa036743@wwwmaster.postgresql.org>
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Luke Koops wrote:

> Description:        Stats collector hung on WaitForMultipleObjectsEx while
> attempting to recv a datagram
> Details: 
> 
> While running a load test with 80 processes connected to postgres, of which
> 62 were generating load, the stats collector got blocked on
> WaitForMultipleObjectsEx which was called with INFINITE timeout.  The stack
> trace for the hung thread follows:


> ntdll.dll!NtWaitForMultipleObjects+0xc
> kernel32.dll!WaitForMultipleObjectsEx+0x11a
> postgres.exe!pgwin32_waitforsinglesocket+0x1ed
> postgres.exe!pgwin32_recv+0x90
> postgres.exe!PgstatCollectorMain+0x17f
> postgres.exe!SubPostmasterMain+0x33a
> postgres.exe!main+0x168
> postgres.exe!__tmainCRTStartup+0x10f
> kernel32.dll!BaseProcessStart+0x23

I have seen this problem too.  The process seems stuck for no good
reason.  I wondered at the time if it could be a kernel issue.  I
remember trying to send some data to the collector to verify whether
it'd wake up, but no luck.  (I mean I couldn't find a way to do it on
Windows).

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support