I run a bit of python code that monitors my connection to the greater Internet.
It checks connectivity to the requested target IP addresses, logging both
successes and failures, once every 15 seconds. I see failures quite regularly,
predictably on Sunday nights after midnight when various networks are
undergoing maintenance. I'm trying to use python's multiprocessing library to
run multiple copies in parallel to check connectivity to different parts of the
country (they in no way interact with each other).
On rare occasions (maybe once every couple of months) I get the following
exception and traceback:
Traceback (most recent call last):
File "./CM_Harness.py", line 12, in <module>
Foo = pool.map(monitor, targets) # and hands off two targets
File
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/pool.py",
line 227, in map
return self.map_async(func, iterable, chunksize).get()
File
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/pool.py",
line 528, in get
raise self._value
IndexError: list index out of range
The code where the traceback occurs is:
#!/usr/bin/env python
""" Harness to call multiple parallel copies
of the basic monitor program
"""
from multiprocessing import Pool
from Connection_Monitor import monitor
targets = ["8.8.8.8", "www.ncsa.edu"]
pool = Pool(processes=2) # start 2 worker processes
Foo = pool.map(monitor, targets) # and hands off two targets
Line 12, in my code is simply the line that launches the underlying monitor
code. I'm assuming that the real error is occurring in the monitor program
that is being launched, but I'm at a loss as to what to do to get a better
handle on what's going wrong. Since, as I said, I see failures quite regularly,
typically on Sunday nights after midnight when various networks are undergoing
maintenance, I don't _think_ the exception is being triggered by that sort of
failure.
When I look at the pool module, the error is occurring in get(self,
timeout=None) on the line after the final else:
def get(self, timeout=None):
self.wait(timeout)
if not self._ready:
raise TimeoutError
if self._success:
return self._value
else:
raise self._value
Python v 2.7.3, from Python.org, running on Mac OS-X 10.8.3
Thanks for any suggestions,
Bill
--
http://mail.python.org/mailman/listinfo/python-list
