G'day,
From: "Anthony Baxter" anthony@interlink.com.au
On Thursday 20 January 2005 12:43, Donovan Baarda wrote:
On Wed, 2005-01-19 at 13:37 +0000, Michael Hudson wrote:
The main oddness about python threads (before 2.3) is that they run with all signals masked. You could play with a C wrapper (call setprocmask, then exec fop) to see if this is what is causing the problem. But please try 2.4.
Python 2.4 does indeed fix the problem. Unfortunately we are using Zope 2.7.4, and I'm a bit wary of attempting to migrate it all from 2.3 to 2.4. Is there any wa this "Fix" can be back-ported to 2.3?
It's extremely unlikely - I couldn't make myself comfortable with it when attempting to figure out it's backportedness. While the current behaviour on 2.3.4 is broken in some cases, I fear very much that the new behaviour will break other (working) code - and this is something I try very hard to avoid in a bugfix release, particularly in one that's probably the final one of a series.
Fundamentally, the answer is "don't do signals+threads, you will get burned". For your application, you might want to instead try
In this case it turns out to be "don't do exec() in a thread, because what you exec can have all it's signals masked". That turns out to be a hell of a lot of things; popen, os.command, etc. They all only work OK in a threaded application if what you are exec'ing doesn't use any signals.
something where you write requests to a file in a spool directory, and have a python script that loops looking for requests, and generates responses. This is likely to be much simpler to debug and work with.
Hmm, interprocess communications; great fun :-) And no spawning the process from within the zope application; it's gotta be a separate daemon.
Actually, I've noticed that zope often has a sorta zombie "which" process which it spawns. I wonder it this is a stuck thread waiting for some signal...
---------------------------------------------------------------- Donovan Baarda http://minkirri.apana.org.au/%7Eabo/ ----------------------------------------------------------------