Different behavior with multiprocessing

Chris Angelico rosuav at gmail.com
Mon Mar 4 16:44:44 CET 2013


On Tue, Mar 5, 2013 at 2:35 AM, Tomas Kotal <tomas.kotal at gmail.com> wrote:
> Seems like I found the problem: os._exit probably takes as parametr unsigned char, so it uses as error code whatever value it gets modulo 256:
>
> os._exit(1)  # process.exitcode == 1
> os._exit(255)  # process.exitcode == 255
> os._exit(256)  # process.exitcode == 0
> os._exit(257)  # process.exitcode == 1
> os._exit(32512)  # process.exitcode == 0
>
> So on Linux it's necesary to call something like this:
> os._exit( os.system(cmd) >> 8 )
>
> Because the first byte of return value on Linux is number of signal which kills the process and the second one is actual exit code.

Yep. I had a reply part-written but you beat me to it! That is indeed
what you need if you want to chain return values.

However, why are you using os._exit? Check out the note here:

http://docs.python.org/2/library/os.html#os._exit

ChrisA



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