Re: Cyrus 2.1.9 on Solaris 8 - occasional deadlocks on individual users

From: Rob Siemborski (no email)
Date: Tue Sep 10 2002 - 13:02:53 EDT

On Tue, 10 Sep 2002, Steve Barber wrote:

> I'm not certain exactly what we're deadlocking on (is there a good way
> to find out for sure?) but have been assuming that it's the user's
> .seen file. Maybe it's an index file? It seems to affect lmtpd

Finding out what file it is would be the first step... Use lsof or
possibly pfiles to fingure out what file is being locked.

> fcntl(7, F_SETLKW, 0xFFBEF3B4) (sleeping...)

(in your case, file descriptor 7 seems to be the problem). Are you sure
that *all* of the user's imapds are blocking on locking the same file?

If not, find out what the imapd that is actually holding the lock on the
file is doing (a gdb backtrace might help with this).

> and imapd at least. We notice it through lmtpd hanging (see below);
> we don't know at this point what (if anything) the user is seeing on
> the imap side. There may be a correlation with dialup users here;
> it could be possible that this is happening when a user's session gets
> uncleanly disconnected, but that's speculation right now.

This is possible, since the session may not time out for another half an
hour. A place where it is known that this can occur is in an APPEND. We
have to lock the mailbox while waiting for network data to arrive, but if
the client disconnects, the process will fail to notice for some time)


Rob Siemborski * Andrew Systems Group * Cyert Hall 207 * 412-268-7456
Research Systems Programmer * /usr/contributed Gatekeeper

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