[Zope] Hang while waiting for external process

[Paul Winkler]

I'm using zope 2.4.3 on linux (redhat 7 with kernel 2.4.14), playing
around with the Photo product (nice one!). I've had a few zope
freezes, and finally found a pattern: Occasionally, if using
ImageMagick to do the rendering for Photo, convert will fail to
complete and Zope will then become completely unresponsive. Browser
requests do nothing.

This is weird. I can understand how one of the Zope threads might get
stuck waiting for the never-ending external process; but why should
Zope become completely unresponsive? Shouldn't the other threads keep
responding?

And is there a way to set a timeout for an external process, such that
zope can recover if it fails to return for too long?


Here's output of ps showing the defunct convert process:
(snip)

 891 pts/0    S      0:00 python2.1 /home/pw/Downloads/Zope/z2.py -M /home/pw/C
 896 pts/0    S      0:09  \_ /usr/local/bin/python2.1 /home/pw/Downloads/Zope/
 919 pts/0    S      0:00      \_ /usr/local/bin/python2.1 /home/pw/Downloads/Z
 920 pts/0    S      0:29          \_ /usr/local/bin/python2.1 /home/pw/Downloa
1001 pts/0    Z      0:00          |   \_ [convert <defunct>]
 921 pts/0    S      0:05          \_ /usr/local/bin/python2.1 /home/pw/Downloa
 922 pts/0    S      0:00          \_ /usr/local/bin/python2.1 /home/pw/Downloa
 923 pts/0    S      0:00          \_ /usr/local/bin/python2.1 /home/pw/Downloa

I can then get zope to restart by killing any of the zope PIDs.

Here's the big M log leading up to the freeze - nothing unusual:...
requestprofiler.py doesn't show any hangs in this log...

$ tail -f bigM 
E 147423764 2001-11-15T17:36:05 
B 143413564 2001-11-15T17:36:16 GET /test_crap/my_image_library/nothing
I 143413564 2001-11-15T17:36:16 0
A 143413564 2001-11-15T17:36:16 500 2485
E 143413564 2001-11-15T17:36:16 
B 147432596 2001-11-15T17:36:25 GET /test_crap/my_image_library/lilaq-logo.jpg
I 147432596 2001-11-15T17:36:25 0
A 147432596 2001-11-15T17:36:25 304 282
E 147432596 2001-11-15T17:36:25 


-- 

paul winkler
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