Re: "could not reattach to shared memory" captured in buildfarm

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org, Dave Page <dpage(at)postgresql(dot)org>
Subject: Re: "could not reattach to shared memory" captured in buildfarm
Date: 2009-05-04 14:17:27
Message-ID: 49FEF8F7.9040809@hagander.net
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Tom Lane wrote:
> Magnus Hagander <magnus(at)hagander(dot)net> writes:
>> Somebody else mentioned, and IIRC I talked to Dave about this before,
>> that this could be because the address is no longer available. The
>> reason for this could be some kind of race condition in the backends
>> starting - the address is available when the postmaster starts and thus
>> it's used, but when a regular backend starts, the memory is used for
>> something else.
>
> How is it no longer available, when the new backend is a brand new
> process? The "race condition" bit seems even sillier --- if there
> are multiple backends starting, they're each an independent process.

Because some other DLL that was loaded on process startup allocated
memory differently - in a different order, different size because or
something, or something like that.

I didn't mean race condition between backends. I meant against a
potential other thread started by a loaded DLL for initialization.
(Again, things like antivirus are known to do this, and we do see these
issues more often if AV is present for example)

//Magnus

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