How to limit and queue up processes in Python












0














Lets say I have 10000 tasks at hand. How can I process them in parallel, running precisely 8 processes at any time? The moment a task is finished, the next task should be fetched for execution immediately.



for e in arr:
pr=Process(target=execute, args=(q,e))
pr.start()
pr.join()


I want to do this because my CPU has only 8 hardware threads. Swarming it with 10000 tasks at once will slow down the overall computation due to the switching overhead. My memory is also limited.



(Edit: This is not a duplicate of this question as I am not asking how to fork a process.)










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  • 3




    Look at the Pool classes in the docs
    – James K Polk
    Nov 12 '18 at 5:11






  • 1




    Possible duplicate of How to process a list in parallel in Python?
    – U9-Forward
    Nov 12 '18 at 5:13










  • I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
    – Chong Lip Phang
    Nov 12 '18 at 5:17
















0














Lets say I have 10000 tasks at hand. How can I process them in parallel, running precisely 8 processes at any time? The moment a task is finished, the next task should be fetched for execution immediately.



for e in arr:
pr=Process(target=execute, args=(q,e))
pr.start()
pr.join()


I want to do this because my CPU has only 8 hardware threads. Swarming it with 10000 tasks at once will slow down the overall computation due to the switching overhead. My memory is also limited.



(Edit: This is not a duplicate of this question as I am not asking how to fork a process.)










share|improve this question




















  • 3




    Look at the Pool classes in the docs
    – James K Polk
    Nov 12 '18 at 5:11






  • 1




    Possible duplicate of How to process a list in parallel in Python?
    – U9-Forward
    Nov 12 '18 at 5:13










  • I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
    – Chong Lip Phang
    Nov 12 '18 at 5:17














0












0








0







Lets say I have 10000 tasks at hand. How can I process them in parallel, running precisely 8 processes at any time? The moment a task is finished, the next task should be fetched for execution immediately.



for e in arr:
pr=Process(target=execute, args=(q,e))
pr.start()
pr.join()


I want to do this because my CPU has only 8 hardware threads. Swarming it with 10000 tasks at once will slow down the overall computation due to the switching overhead. My memory is also limited.



(Edit: This is not a duplicate of this question as I am not asking how to fork a process.)










share|improve this question















Lets say I have 10000 tasks at hand. How can I process them in parallel, running precisely 8 processes at any time? The moment a task is finished, the next task should be fetched for execution immediately.



for e in arr:
pr=Process(target=execute, args=(q,e))
pr.start()
pr.join()


I want to do this because my CPU has only 8 hardware threads. Swarming it with 10000 tasks at once will slow down the overall computation due to the switching overhead. My memory is also limited.



(Edit: This is not a duplicate of this question as I am not asking how to fork a process.)







python python-3.x process parallel-processing python-3.6






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 12 '18 at 5:31

























asked Nov 12 '18 at 5:08









Chong Lip Phang

2,83843041




2,83843041








  • 3




    Look at the Pool classes in the docs
    – James K Polk
    Nov 12 '18 at 5:11






  • 1




    Possible duplicate of How to process a list in parallel in Python?
    – U9-Forward
    Nov 12 '18 at 5:13










  • I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
    – Chong Lip Phang
    Nov 12 '18 at 5:17














  • 3




    Look at the Pool classes in the docs
    – James K Polk
    Nov 12 '18 at 5:11






  • 1




    Possible duplicate of How to process a list in parallel in Python?
    – U9-Forward
    Nov 12 '18 at 5:13










  • I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
    – Chong Lip Phang
    Nov 12 '18 at 5:17








3




3




Look at the Pool classes in the docs
– James K Polk
Nov 12 '18 at 5:11




Look at the Pool classes in the docs
– James K Polk
Nov 12 '18 at 5:11




1




1




Possible duplicate of How to process a list in parallel in Python?
– U9-Forward
Nov 12 '18 at 5:13




Possible duplicate of How to process a list in parallel in Python?
– U9-Forward
Nov 12 '18 at 5:13












I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
– Chong Lip Phang
Nov 12 '18 at 5:17




I don't think it is a duplicate of that question, as I am not asking how to fork a process. Anyway, Pool is probably the solution to my problem. Thanks, James!
– Chong Lip Phang
Nov 12 '18 at 5:17












2 Answers
2






active

oldest

votes


















0














I think if you split the "for" loop for join statement your problem might be solved. Right now you start a fork and want the result to come back and go do another fork process. And no fork is closed right now.



for e in arr:
pr=Process(target=execute, args=(q,e))
pr.start()

for e in arr:
pr.join()


Or just go with pool and map functions.






share|improve this answer

















  • 1




    I am going for Pool.
    – Chong Lip Phang
    Nov 12 '18 at 5:27



















0














For Pool to work here I need to call get() too.



from multiprocessing import Pool
pl=
pool = Pool(8)
for e in arr:
pl.append(pool.apply_async(execute, (e))
for pl2 in pl: pl2.get()





share|improve this answer





















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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    0














    I think if you split the "for" loop for join statement your problem might be solved. Right now you start a fork and want the result to come back and go do another fork process. And no fork is closed right now.



    for e in arr:
    pr=Process(target=execute, args=(q,e))
    pr.start()

    for e in arr:
    pr.join()


    Or just go with pool and map functions.






    share|improve this answer

















    • 1




      I am going for Pool.
      – Chong Lip Phang
      Nov 12 '18 at 5:27
















    0














    I think if you split the "for" loop for join statement your problem might be solved. Right now you start a fork and want the result to come back and go do another fork process. And no fork is closed right now.



    for e in arr:
    pr=Process(target=execute, args=(q,e))
    pr.start()

    for e in arr:
    pr.join()


    Or just go with pool and map functions.






    share|improve this answer

















    • 1




      I am going for Pool.
      – Chong Lip Phang
      Nov 12 '18 at 5:27














    0












    0








    0






    I think if you split the "for" loop for join statement your problem might be solved. Right now you start a fork and want the result to come back and go do another fork process. And no fork is closed right now.



    for e in arr:
    pr=Process(target=execute, args=(q,e))
    pr.start()

    for e in arr:
    pr.join()


    Or just go with pool and map functions.






    share|improve this answer












    I think if you split the "for" loop for join statement your problem might be solved. Right now you start a fork and want the result to come back and go do another fork process. And no fork is closed right now.



    for e in arr:
    pr=Process(target=execute, args=(q,e))
    pr.start()

    for e in arr:
    pr.join()


    Or just go with pool and map functions.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 12 '18 at 5:22









    ytamer

    316




    316








    • 1




      I am going for Pool.
      – Chong Lip Phang
      Nov 12 '18 at 5:27














    • 1




      I am going for Pool.
      – Chong Lip Phang
      Nov 12 '18 at 5:27








    1




    1




    I am going for Pool.
    – Chong Lip Phang
    Nov 12 '18 at 5:27




    I am going for Pool.
    – Chong Lip Phang
    Nov 12 '18 at 5:27













    0














    For Pool to work here I need to call get() too.



    from multiprocessing import Pool
    pl=
    pool = Pool(8)
    for e in arr:
    pl.append(pool.apply_async(execute, (e))
    for pl2 in pl: pl2.get()





    share|improve this answer


























      0














      For Pool to work here I need to call get() too.



      from multiprocessing import Pool
      pl=
      pool = Pool(8)
      for e in arr:
      pl.append(pool.apply_async(execute, (e))
      for pl2 in pl: pl2.get()





      share|improve this answer
























        0












        0








        0






        For Pool to work here I need to call get() too.



        from multiprocessing import Pool
        pl=
        pool = Pool(8)
        for e in arr:
        pl.append(pool.apply_async(execute, (e))
        for pl2 in pl: pl2.get()





        share|improve this answer












        For Pool to work here I need to call get() too.



        from multiprocessing import Pool
        pl=
        pool = Pool(8)
        for e in arr:
        pl.append(pool.apply_async(execute, (e))
        for pl2 in pl: pl2.get()






        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 12 '18 at 6:02









        Chong Lip Phang

        2,83843041




        2,83843041






























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