What's the modern way to solve Plone deadlock issues?

Question

I currently have a Plone 4.3.8 site where editing a portlet causes a deadlock.

I'm trying to find tools to fix this, but most deadlock tools don't work & I'm not getting good information (IMO) from those that at least run.

I've tried:

• z3c.deadlockdebugger => can't get to a stacktrace
• ZopeHealthWatcher => can't see the results on command line (or webpage)
• Products.LongRequestLogger => perhaps the best so far, gives me some log output - but it's stack traces focus on Diazo code, but the problem still occurs when Diazo isn't in scope (running against 127.0.0.1)
• gdb attach - just landed me in C code
• winpdb => it can't attach to running processes in the same way that gdb can (only to processes started with the intention of attachment by winpdb)
• Products.signalstack (OR Products.signalstacklogger) => USR1 signal just shuts down a zope process!

Note: z3c.deadlockdebugger (and things that depend on it) needs checked out source code to drop the threadframe dependency.

My situation seems to be linked to product upgrades - probably one or both of either plone.app.contenttypes or plone.app.multilingual, an empty site doesn't have this issue, but I obviously I need my site data!

What should I do to progress this?

EDIT:

I believe Maurits answer to be the most correct one, but it didn't work in my case. What I ended up doing was using pdb to track down the point at which the code was hanging (in plone.app.debugtoolbar as it happens)

Answer 1

You say that using the USR1 signal shuts down Zope when using Products.signalstack. But no special packages should be necessary, so I wonder if adding signalstack has this side effect of shutting down Zope.

At least for me, a few weeks ago, this worked fine on a Plone 4.3.something site:

kill -USR1 $(cat var/zeoclient.pid)

Answer 2

Although the @maurits answer is right (and the simplest ones) sometimes I had issues seeing the traceback resulting from the kill command: sometimes is found on the event log, sometimes on the shell.

I prefer the integration of the buildout with haufe.requestmonitoring, configuring also the monitor long running requests feature. You will see the deadlocked traceback in your event log and also you activate a tool for monitoring low performance on your Plone.