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POHow to spawn parallel child processes on a multi-processor system?
 

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  1. POHow to spawn parallel child processes on a multi-processor system?
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    <p>I have a Python script that I want to use as a controller to another Python script. I have a server with 64 processors, so want to spawn up to 64 child processes of this second Python script. The child script is called:</p> <pre><code>$ python create_graphs.py --name=NAME </code></pre> <p>where NAME is something like XYZ, ABC, NYU etc.</p> <p>In my parent controller script I retrieve the name variable from a list:</p> <pre><code>my_list = [ 'XYZ', 'ABC', 'NYU' ] </code></pre> <p>So my question is, what is the best way to spawn off these processes as children? I want to limit the number of children to 64 at a time, so need to track the status (if the child process has finished or not) so I can efficiently keep the whole generation running.</p> <p>I looked into using the subprocess package, but rejected it because it only spawns one child at a time. I finally found the multiprocessor package, but I admit to being overwhelmed by the whole threads vs. subprocesses documentation.</p> <p>Right now, my script uses <code>subprocess.call</code> to only spawn one child at a time and looks like this:</p> <pre><code>#!/path/to/python import subprocess, multiprocessing, Queue from multiprocessing import Process my_list = [ 'XYZ', 'ABC', 'NYU' ] if __name__ == '__main__': processors = multiprocessing.cpu_count() for i in range(len(my_list)): if( i &lt; processors ): cmd = ["python", "/path/to/create_graphs.py", "--name="+ my_list[i]] child = subprocess.call( cmd, shell=False ) </code></pre> <p>I really want it to spawn up 64 children at a time. In other stackoverflow questions I saw people using Queue, but it seems like that creates a performance hit?</p>
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    1. COuse enumerate instead of range+len combination
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