Re: fsync and semctl errors with 8.1.5/win32

From: "Thomas H(dot)" <me(at)alternize(dot)com>
To: "Jeremy Haile" <jhaile(at)fastmail(dot)fm>, <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: fsync and semctl errors with 8.1.5/win32
Date: 2006-11-30 15:10:37
Message-ID: 029f01c71491$b17fe1b0$0201a8c0@iwing
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> Did you run into problems where transactions would hang? If so, did
> those disappear in 8.2?

well, i wasn't really able to exactly determine under what conditions that
xlog bug appeared in our case. tho it always was when lots of data is
imported at once within one transaction. under normal load i've never seen
the xlog bug. as far as i know it was some sort of lifelock: as with the
other error messages, another postgres.exe kept a lock of the xlog file,
which the bgwriter-process wanted to rename which lead to the complete halt
of the db system, due to the importance of xlog/bgwriter. you can force an
unload of the locked xlog file handle in processmon, and postgresql will
resume "normally".

i had a transaction lately that created 7gb of xlog-files (vacuum full of a
mid-sized table) without any xlog-lockup, so i guess this problem is really
fixed in the latest 8.2 build :-)

if you have hanging transactions but other db activity works well, i would
rather guess its a side effect of the other file problems with the
relation-files that can't be renamed. i've never been able to see any impact
of that error message. even when it appears 10 times a second everything
seems "ok". but on the other side, in our case, we use the database as a web
backend and have always around 20-30 concurrent connections, so its hard to
debug.

- thomas

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