Python time.sleep() raises exception in multi-threaded app

Binary package hint: python2.5-minimal

Ubuntu 7.10
Python 2.5.1 (r251:54863, Oct 5 2007, 13:36:32)

Sometimes, time.sleep() in python raises "IOError: [Errno 22] Invalid argument" in multi-threaded app. This exception is similar to what is raised when sleep()'s argument is non-positive, but it isn't the case. I believe that it happens (rarely) when in another thread an exception is raised (even if it's catched later). It happens both when I call sleep() directly from my code or indirectly from a standard python library (for example threading.Condition class uses sleep, and the bug reproduces with it, too).

Here goes the script with which I reproduce this bug (about two or threee times in ten runs of the script). With the same script at Debian 3.1, python 2.4.1, I can't reproduce the bug (and I believe that it really doesn't happen there).

#!/usr/bin/python2.5
import threading, time, random, sys

stopped = False

def do_sleep():
    while not stopped:
        time.sleep(random.random()/1000 + 0.001)

class MyException(Exception):
    pass

def do_raise():
    while not stopped:
        try:
            time.sleep(0.01)
            raise MyException
        except:
            pass

sleepers = [threading.Thread(target = do_sleep) for i in range(100)]
raisers = [threading.Thread(target = do_raise) for i in range(100)]

for s in sleepers: s.start()
for s in raisers: s.start()

for i in range(100):
    print ',',
    sys.stdout.flush()
    time.sleep(1)
stopped = True

for s in sleepers: s.join()
for s in raisers: s.join()
print '.'