[Zope] Can't stop Zope, machine hanging

[Ken Ara]

Thank you, Dieter, for your valuable insights and
information. I am forwarding this to my ISP.

--- Dieter Maurer <dieter at handshake.de> wrote:

> Ken Ara wrote at 2006-9-5 07:47 -0700:
> >...
> >Of immediate concern to me is whether I can do
> >anything to prevent this happening again. From time
> to
> >time, my Zope hangs, usually because of an attack
> by a
> >bad robot requesting lots of complex pages and
> sending
> >no-cache headers. Then I am able to restart Zope
> and
> >all is well. For a while, when these attacks were
> >frequent, I had a crontab to zopectl restart every
> >hour. 
> 
> There are solutions (I think "daemontools", but may
> be wrong)
> that can automate this more intelligently than a
> cronjob.
> 
> We have our own check server which polls Zope and if
> it does
> not respond in time restarts it.
> 
> 
> >But this event was different and I would like to
> know
> >if anyone thinks that something I am doing wrong
> could
> >cause the Zope process to become 'unkillable' and
> >require a reset of the machine. Has anyone else had
> >this problem?
> 
> Up to Python 2.3.4 and Python 2.4.0 (fixed in Python
> 2.3.5 and Python 2.4.1),
> a fatal signal (like "SIGSEGV") could bring Zope in
> a state where
> its main thread was killed but the child threads
> were still alive.
> These child threads could only be killed with "kill
> -9".
> 
> Although we now use Python 2.4.1, I have seen a
> similar problem just
> a few days ago. But almost surely, this has to do
> with the
> Java Virtual Machine which we now also integrate in
> our Zope instances.
> 
> 
> However, when even "kill -9" (as "root") is no
> longer able to kill a process,
> then the process is somewhere deep in the operating
> system (where
> signal handling is deactivated for consistency
> reasons).
> Usually, this indicates a network problem.
> 
> And if your operating system is no longer ready to
> shutdown, then
> you have an even more fundamental problem -- maybe,
> too, connected
> to network problems.
> 
> 
> I fear we cannot help you much -- as a intensive
> analysis of your
> system would be necessary in order to find the
> causes of your
> problems.
> 
> >I would have liked to perform some diagnostic on
> the
> >machine in its stuck state, but neither I nor the
> ISP
> >knew where to start.
> 
> Usually, one would start with an analysis of the
> operating system
> log files.
> 
> If they do not tell anything, then one would check
> what is still
> working (e.g. is the console still responding, does
> it still
> observe the magic "CTRL-ALT-DEL" reboot key
> sequence), which commands
> fail and in what way, ...
> 
> 
> 
> -- 
> Dieter
> 


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