DiagnosingHangProblems

MarcusCollins posed this list of useful questions in reply to a reported hang problem:

Does Zope hang when you access the management interface using http://path/to/zope/manage_main or ftp?
Does Zope hang if you run in single threaded mode (z2.py -t 1)?
Are you using the default NUMBER_OF_THREADS (4)?
Are you using any database adaptors and, if so, which versions?
Is the hanging more or less frequent in Zope 2.1.6 than in 2.1.4?
What method of access (HTTP/PCGI/FCGI) do you use for the management interface? Is this the same protocol you use for the rest of the site?
Are you using a binary distribution of Zope, or have you compiled from source? Ditto for python.
Can you cause Zope to hang by refreshing the page a number of times in quick succession, or by stopping the request and then reloading?

Ross Lazarus - April 17, Redhat6.1 on intel hardware. Binary or source install (no difference) 2.1.6. Main Products in use - LDAPAdapter?, ZWiki, SybaseDA2? (current version). Others installed, but the problem didn't go away when I did a clean install and added just the things needed to run the main application. Main app. is a big, complex zclasses based curriculum document management thing with some external python methods - most often used to make static representations of zope objects since we serve static pages using apache. I've tried to attain thread safety with all the external methods, but may have missed something.

Specific responses:-

Sometimes - seems to be more likely, particulary first thing in the morning, but certainly not necessary - users without access to management screens seem able to crash zope unless single threaded
Never so far.
Was when problems arose
Sybase - latest release of SybaseDAV2?
More frequent in 2.1.6 I think, but we've only really started hammering this app since February.
Straight ZServer? - I tried FastCGI via apache for a while - no difference; it was slower and still crashed so I went back to ZServer?
No difference whether I used a source or binary install. Normally, everything is compiled from source here but I tried a binary release of 2.1.6 just in case - no difference
Now that I'm using -t 1, no !