odd runtime error

[James Mills]

On Thu, Dec 2, 2010 at 10:59 AM, Chris Rebert <clp2 at rebertia.com> wrote:
> On Wed, Dec 1, 2010 at 4:49 PM, David Brown <dmlb2000 at gmail.com> wrote:
>> So I'm not subscribed to python-list but would like to get an answer
>> to my question. I've made a small test program that dumps a
>> RuntimeError and I'd like to know why.
>>
>> $ python test2.py
>> doing stuff
>> Traceback (most recent call last):
>>  File "test2.py", line 3, in <module>
>>    import test
>> RuntimeError: not holding the import lock
>> child 3693 exited with 256
>> $
>>
>> Here's the setup, there's two files test.py and test2.py
>>
>> $ cat test.py
>> #!/usr/bin/python
>>
>> import os, sys
>>
>> if os.fork() == 0:
>>        print "doing stuff"
>>        sys.exit()
>>
>> print "child %d exited with %d" % os.wait()

Assuming you actually want to fork
and do something inside the forked child
process, the correct implementation is this:

$ cat test.py
#!/usr/bin/env python

import os
from time import sleep

def main():
    print "parent %d started" % os.getpid()
    if os.fork() == 0:
        print "doing stuff"
        sleep(5)
        print "done"
        raise SystemExit, 0
    print "child %d exited with %d" % os.wait()

if __name__ == "__main__":
	main()

cheers
James

-- 
-- James Mills
--
-- "Problems are solved by method"