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Re: PL/TCL Patch to prevent postgres from becoming multithreaded

From: "Marshall, Steve" <smarshall(at)wsi(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-patches(at)postgresql(dot)org>
Subject: Re: PL/TCL Patch to prevent postgres from becoming multithreaded
Date: 2007-09-21 11:55:24
Message-ID: 8536F69C1FCC294B859D07B179F069440A789512@EXCHANGE.ad.wsicorp.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
I'm glad to see the patch making its way through the process.  I'm also
glad you guys do comprehensive testing before accepting it, since we are
only able to test in a more limited range of environments.

We have applied the patch to our 8.2.4 installations and are running it
in a high transaction rate system (processing lots and lots of
continually changing weather data).  Let me know if there is any
information we could provide that would be of help in making the
back-patching decision.

Yours,
Steve Marshall

-----Original Message-----
From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us] 
Sent: Thursday, September 20, 2007 8:33 PM
To: Marshall, Steve
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: [PATCHES] PL/TCL Patch to prevent postgres from becoming
multithreaded 

"Marshall, Steve" <smarshall(at)wsi(dot)com> writes:
> There is a problem in PL/TCL that can cause the postgres backend to 
> become multithreaded.   Postgres is not designed to be multithreaded,
so 
> this causes downstream errors in signal handling.  We have seen this 
> cause a number of "unexpected state" errors associated with 
> notification handling; however, unpredictable signal handling would be

> likely to cause other errors as well.

I've applied this patch to CVS HEAD (8.3-to-be).  I'm a bit hesitant to
back-patch it however, at least not till it gets through some beta
testing.

Thanks for the detailed explanation, test case, and patch!

			regards, tom lane


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