[Zope] Zope 2.8.4 strange behavior

[Paul Winkler]

On Mon, Nov 28, 2005 at 08:19:23PM +0100, Dieter Maurer wrote:
> Paul Winkler wrote at 2005-11-27 21:17 -0500:
> > ...
> >I've seen the same symptoms a number of times recently with zope 2.7.x.
> >In our case, it seems to be related to ZEO. Zope seems to have lost
> >its connection to ZEO but doesn't realize it somehow.  My theory is
> >that the symptom starts when all worker threads are waiting for objects
> >that aren't in the ZEO client cache, so they're all waiting on ZEO
> >requests.
> 
> Do you have a firewall between Zope and ZEO?

Yes, we do, and it is under control of another part of the company 
:-(
 
> Usually, the OS can inform both ends of a connection when
> the connection is torn down.
> However, some firewalls tear a connection down in a way that
> the endpoints do not get informed.

I suspected as much... thanks.
 
> We had to implement a keep alive mechanism to prevent our firewall
> from behaving in this nasty way.

OK. Can you give a high-level summary of what you did?  I thought of
using heartbeat to detect loss of connection, but I'm not sure what I
could do on failure short of restarting Zope.

-- 

Paul Winkler
http://www.slinkp.com