multiprocessing: child process race to answer

Mark Lawrence breamoreboy at yahoo.co.uk
Sun Nov 3 11:24:54 CET 2013


On 03/11/2013 10:10, cappleman at gmail.com wrote:
> On Friday, November 1, 2013 10:35:47 PM UTC-4, smhall05 wrote:
>> I am using a basic multiprocessing snippet I found:
>>
>>
>>
>> #-----------------------------------------------------
>>
>> from multiprocessing import Pool
>>
>>
>>
>> def  f(x):
>>
>>      return x*x
>>
>>
>>
>> if __name__ == '__main__':
>>
>>      pool = Pool(processes=4)              # start 4 worker processes
>>
>>      result = pool.apply_async(f, [10])    # evaluate "f(10)" asynchronously
>>
>>      print result.get(timeout=1)
>>
>>      print pool.map(f, range(10))          # prints "[0, 1, 4,..., 81]"
>>
>> #---------------------------------------------------------
>>
>>
>>
>> I am using this code to have each process go off and solve the same problem, just with different inputs to the problem. I need to be able to kill all processes once 1 of n processes has come up with the solution. There will only be one answer.
>>
>>
>>
>> I have tried:
>>
>>
>>
>> sys.exit(0) #this causes the program to hang
>>
>> pool.close()
>>
>> pool.terminate
>>
>>
>>
>> These still allow further processing before the program terminates. What else can I try? I am not able to share the exact code at this time. I can provide more detail if I am unclear. Thank you
>
> You could take a look at the Mutiprocessing module capabilities for exchanging objects between processes:
>
> http://docs.python.org/3.3/library/multiprocessing.html#exchanging-objects-between-processes
>

Would you please read and action this as it prevents the double line 
spacing that you can observe above, thanks 
https://wiki.python.org/moin/GoogleGroupsPython

-- 
Python is the second best programming language in the world.
But the best has yet to be invented.  Christian Tismer

Mark Lawrence




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