Re: Large object loading stalls

From: Michael Akinde <michael(dot)akinde(at)met(dot)no>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Large object loading stalls
Date: 2009-02-25 11:45:37
Message-ID: 49A52F61.3070402@met.no
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Tom Lane wrote:
> Michael Akinde <michael(dot)akinde(at)met(dot)no> writes:
>
>> Tom Lane wrote:
>>
>>> In the past we've seen this type of thing caused by multithreaded
>>> client programs in which more than one thread tried to use the same
>>> PGconn object without adequate interlocking.
>>>
>> Our application is single-threaded, so it seems unlikely that we are
>> running into a problem with that.
>>
>
> Well, maybe you've found an actual bug then; but without a test case
> that other people can poke at, it's hard to investigate.
>
>> The only thing I can think of right now, is that we are running a
>> Postgres 8.3 on Debian Etch (so a backported debian package), whereas
>> the libraries linked into our application are older library version
>> (libpq4 and libpqxx 2.6.8).
>>
>
> Older libpq versions should work fine with an 8.3 server --- if they
> don't, that's a bug in itself. I do not know the status of libpqxx
> though; you might want to check whether there are known bugs in that
> version.
>
There are a few known bugs in pqxx that *might* relate to our code; for
instance, we use prepared statements, and this is an area that has seen
a good deal of work from 2.6.8 to 2.6.9.

The test work at the moment is hampered by our server section needing to
physically move some of our development & test servers this week, but if
upgrading pqxx doesn't seem to eliminate the problem, I'll do some work
to see if I can recreate the problem in an isolated setting.

Regards,

Michael A.

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