[Zope] ZServer stops responding !? Help !?

[Jean-Francois.Doyon at CCRS.NRCan.gc.ca]

G'day,

I've got a rather bizarre but catastrophic problem.

ZServer seems to stop responding.  Sometimes it does so after days of
running, sometimes after a few seconds or minutes of uptime.

I know it's ZServer because I can talk to the monitoring port without
problem.

Also, the apache processes just pile up up to the limit allowed,
suggesting the proxying is not getting replies from the downstream
server.

The strange thing is the cause seems to be occacional, or vary.  For
hours on end I can sit there and restart it, and within minutes it stops
responding ... Then suddenly the problem "disappears", I restart it, and
I wait .... and nothing happens, it just keeps running.  Nothing else
abnormal is going on the server so far as I can tell, there is very
little memory swapped, and the CPU usage is not abnormally high.

I used to have this problem very very rarely in the past, but since I
upgraded to Zope 2.7, it seems to have gotten much worse :(

I tried accesing the DebugPanel from the monitor, but can't seem to get
it to do anything useful ... I don't know where else to look to find the
cause of this.

This causes serious uptime problem on our main, high traffic site, which
is Very Bad.

I'm on RedHat 7.3 (fully patched)
Python 2.3.3 (custom compiled)
Zope 2.7
CMF 1.4.x (I forget ... the latest!)
Psycopg (Latest also)
And a variety of other products.

Thanks,
J.F.