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POAlways run a constant number of subprocesses in parallel
 

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    <p>I want to use subprocesses to let 20 instances of a written script run parallel. Lets say i have a big list of urls with like 100.000 entries and my program should control that all the time 20 instances of my script are working on that list. I wanted to code it as follows:</p> <pre><code>urllist = [url1, url2, url3, .. , url100000] i=0 while number_of_subproccesses &lt; 20 and i&lt;100000: subprocess.Popen(['python', 'script.py', urllist[i]] i = i+1 </code></pre> <p>My script just writes something into a database or textfile. It doesnt output anything and dont need more input than the url.</p> <p>My problem is i wasnt able to find something how to get the number of subprocesses that are active. Im a novice programmer so every hint and suggestion is welcome. I was also wondering how i can manage it once the 20 subprocesses are loaded that the while loop checks the conditions again? I thought of maybe putting another while loop over it, something like</p> <pre><code>while i&lt;100000 while number_of_subproccesses &lt; 20: subprocess.Popen(['python', 'script.py', urllist[i]] i = i+1 if number_of_subprocesses == 20: sleep() # wait to some time until check again </code></pre> <p>Or maybe theres a bette possibility that the while loop is always checking on the number of subprocesses?</p> <p>I also considered using the module multiprocessing, but i found it really convenient to just call the script.py with subprocessing instead of a function with multiprocessing.</p> <p>Maybe someone can help me and lead me into the right direction. Thanks Alot!</p>
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