Monitoring a Zope 2 application

We have a simple need for a customer project that runs a Zeo server and a few Zeo clients : being able to check the status of every Zeo client, and monitor what they are doing.

DeadlockDebugger almost provides this feature since it is able to produce a dump of the execution stack for every thread a Zope instance is running.

Based on this tool, I have developed ZopeHealthWatcher, that provides a console script to query a Zope instance, and get back a status for every running thread. It tells you if the thread is idling or if it's running some code. The script also returns an exit code depending on the number of busy threads, so it can be used in tools like Nagios.

When there are 4 or more busy threads, the script will return the execution stacks for every busy thread and some extra info like the system load and memory info. The returned info will be extendable through plug-ins in the next version, but right now the provided info are enough for our needs.

I have also created an HTML version, so when the dump is requested from another tool than the console script (e.g. a browser), it displays a nice human-readable interface (check the PyPI page for more info and a screenshot).

Notice that DeadLockDebugger is hackish since it patches the Zope publisher at startup. But we won't change this part: we need this tool to run from the oldest to the newest Zope 2 version. And the patch just works fine, so...

The provided version should run out of the box in a buildout-based Plone 3 application, but requires manual installation steps on older Plone or CPS versions.

I didn't mention these manual steps in the documentation. I think I am the only person in the world interested in running this tool on the dead-but-still-in-production-in-many-places Nuxeo CPS.

By the way: kudos goes to Marc-Aurèle Darche, who is maintaining CPS for years now, making it one of the most bug-free and stable CMS solution out there. Ok it's probably easier to reach this level of quality since the platform is very stable and only evolves very slowly thanks to Georges Racinet.

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