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Question related to multiprocessing.Process

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  Question related to multiprocessing.Process Cen Wang <iwarobots@gmail.com> - 2013-01-18 20:50 -0800
    Re: Question related to multiprocessing.Process Chris Angelico <rosuav@gmail.com> - 2013-01-19 16:05 +1100
      Re: Question related to multiprocessing.Process Cen Wang <iwarobots@gmail.com> - 2013-01-18 21:33 -0800
      Re: Question related to multiprocessing.Process Cen Wang <iwarobots@gmail.com> - 2013-01-18 21:33 -0800
    Re: Question related to multiprocessing.Process Terry Reedy <tjreedy@udel.edu> - 2013-01-19 06:27 -0500

#37048 — Question related to multiprocessing.Process

Hi, when I use multiprocessing.Process in this way:

from multiprocessing import Process

class MyProcess(Process):
    
    def __init__(self):
        Process.__init__(self)
    
    def run(self):
        print 'x'

p = MyProcess()
p.start()

It just keeps printing 'x' on my command prompt and does not end. But I think MyProcess should print an 'x' and then terminate. I don't why this is happening. I'm using Win7 64 bit, Python 2.7.3. Any idea? Thanks in advance.

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#37050

On Sat, Jan 19, 2013 at 3:50 PM, Cen Wang <iwarobots@gmail.com> wrote:
> Hi, when I use multiprocessing.Process in this way:
>
> from multiprocessing import Process
>
> class MyProcess(Process):
>
>     def __init__(self):
>         Process.__init__(self)
>
>     def run(self):
>         print 'x'
>
> p = MyProcess()
> p.start()
>
> It just keeps printing 'x' on my command prompt and does not end. But I think MyProcess should print an 'x' and then terminate. I don't why this is happening. I'm using Win7 64 bit, Python 2.7.3. Any idea? Thanks in advance.

Multiprocessing on Windows requires that your module be importable. So
it imports your main module, which instantiates another MyProcess,
starts it, rinse and repeat. You'll need to protect your main routine
code:

if __name__=="__main__":
    p = MyProcess()
    p.start()

ChrisA

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#37053

Thanks! It now works!
On Saturday, 19 January 2013 13:05:07 UTC+8, Chris Angelico  wrote:
> On Sat, Jan 19, 2013 at 3:50 PM, Cen Wang <iwarobots@gmail.com> wrote:
> 
> > Hi, when I use multiprocessing.Process in this way:
> 
> >
> 
> > from multiprocessing import Process
> 
> >
> 
> > class MyProcess(Process):
> 
> >
> 
> >     def __init__(self):
> 
> >         Process.__init__(self)
> 
> >
> 
> >     def run(self):
> 
> >         print 'x'
> 
> >
> 
> > p = MyProcess()
> 
> > p.start()
> 
> >
> 
> > It just keeps printing 'x' on my command prompt and does not end. But I think MyProcess should print an 'x' and then terminate. I don't why this is happening. I'm using Win7 64 bit, Python 2.7.3. Any idea? Thanks in advance.
> 
> 
> 
> Multiprocessing on Windows requires that your module be importable. So
> 
> it imports your main module, which instantiates another MyProcess,
> 
> starts it, rinse and repeat. You'll need to protect your main routine
> 
> code:
> 
> 
> 
> if __name__=="__main__":
> 
>     p = MyProcess()
> 
>     p.start()
> 
> 
> 
> ChrisA

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#37054

Thanks! It now works!
On Saturday, 19 January 2013 13:05:07 UTC+8, Chris Angelico  wrote:
> On Sat, Jan 19, 2013 at 3:50 PM, Cen Wang <iwarobots@gmail.com> wrote:
> 
> > Hi, when I use multiprocessing.Process in this way:
> 
> >
> 
> > from multiprocessing import Process
> 
> >
> 
> > class MyProcess(Process):
> 
> >
> 
> >     def __init__(self):
> 
> >         Process.__init__(self)
> 
> >
> 
> >     def run(self):
> 
> >         print 'x'
> 
> >
> 
> > p = MyProcess()
> 
> > p.start()
> 
> >
> 
> > It just keeps printing 'x' on my command prompt and does not end. But I think MyProcess should print an 'x' and then terminate. I don't why this is happening. I'm using Win7 64 bit, Python 2.7.3. Any idea? Thanks in advance.
> 
> 
> 
> Multiprocessing on Windows requires that your module be importable. So
> 
> it imports your main module, which instantiates another MyProcess,
> 
> starts it, rinse and repeat. You'll need to protect your main routine
> 
> code:
> 
> 
> 
> if __name__=="__main__":
> 
>     p = MyProcess()
> 
>     p.start()
> 
> 
> 
> ChrisA

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#37081

On 1/19/2013 12:05 AM, Chris Angelico wrote:
> On Sat, Jan 19, 2013 at 3:50 PM, Cen Wang <iwarobots@gmail.com> wrote:
>> Hi, when I use multiprocessing.Process in this way:
>>
>> from multiprocessing import Process
>>
>> class MyProcess(Process):
>>
>>      def __init__(self):
>>          Process.__init__(self)
>>
>>      def run(self):
>>          print 'x'
>>
>> p = MyProcess()
>> p.start()
>>
>> It just keeps printing 'x' on my command prompt and does not end. But I think MyProcess should print an 'x' and then terminate. I don't why this is happening. I'm using Win7 64 bit, Python 2.7.3. Any idea? Thanks in advance.
>
> Multiprocessing on Windows requires that your module be importable. So
> it imports your main module, which instantiates another MyProcess,
> starts it, rinse and repeat. You'll need to protect your main routine
> code:
>
> if __name__=="__main__":
>      p = MyProcess()
>      p.start()

This is documented in
17.2.3. Programming guidelines
17.2.3.2. Windows

-- 
Terry Jan Reedy

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