Multithreaded python program freezes

[Cameron Simpson]

On 20Dec2009 17:36, Andreas R�sdal <andrearo at pvv.ntnu.no> wrote:
| I have some problems with a http proxy which is implemented
| in Python 2.6. A few times a day, the proxy begins using 100% CPU
| and doesn't work any more.
| 
| I have created a thread dump when the problem occurs here:
| http://www.pvv.ntnu.no/~andrearo/thread-dump.html
| 
| This is a thread dump during normal operation:
| http://www.pvv.ntnu.no/~andrearo/thread-dump-normal.html

These two URLs don't work for me.

[...]
| Any advice on why this Python program appears to freeze? Is there anything
| more I can do to find out why this problem occurs?

Sounds like a livelock:
  http://en.wikipedia.org/wiki/Deadlock#Livelock
or busy lock.

Can you find out which bits of your program are busy?

Are there places in your code that loop, polling for data, instead of
using blocking I/O. With a network proxy, a typical place that might
happen is a loop testing select() (or its poll-like friends) with a short or
zero timeout on inactive file handles.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

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