[Zope] Exception ThreadLock.error: 'release unlocked lock'

[Teemu Yli-Elsilä]

On Tue, 9 Nov 1999, Martijn Pieters wrote:

> >Although apparently not harmful, I do suspect that eventually the process 
> >will run out of threads.
> 
> Hmm.. The error occurs within the THUNKed database adapter, it's a problem 
> with the ThreadLock. I think something goes wrong with the _register method 
> of the THUNK class (either register or self._begin fails), causing the 
> freshly acquired lock to be released again.
> 
> Then, when the transaction is finished, tpc_finish is called, which 
> releases a unlocked lock, which throws the exception. But because the 
> transaction was already finished, we get the aforementioned log message. 
> Zope just continues to run.
>
> The question is, what, if any, side effects does this cause, and how does 
> this problem occur, so we can put an end to it?

In my case the problem is real. I have a UserDb folder at the top level
(/) handling all Zope users. What happens is that a few hours after
inactivity (no accesses) Zope is no longer accepting any logins. You can
view the public pages, but UserDb seems to deny all login attempts. I have
had to restart Zope whenever this occurs to get into the server.

My config again:

- Red Hat Linux 6.0
- Zope 2.0.1 (binary tarball from zope.org)
- Solid RDBMS v2.3
- Jeff Rush's ZODBCDA/Solid (binary tarball)
- UserDb 1.3.0

Is there anything I could do to provide more information in order to get
help solving the problem?

Thank you,
-Teemu