Python multiprocessing class methods -
i'm trying change class field using it's method, when method put doesn't work.
from multiprocessing import process
class multi: def __init__(self): self.x = 20 def loop(self,): in range(1,100): self.x = m = multi() p = process(target=m.loop) p.start() after running program m.x still 20. how possible?
first, want use join, waits process finish before continuing through rest of code.
second, when use multiprocess, creates new instance of m every process. can see when printing self within loop
class multi: def __init__(self): self.x = 20 def loop(self): print(self, 'loop') in range(1, 100): self.x = if __name__ == '__main__': m = multi() print(m, 'main 1') p = process(target=m.loop) p.start() p.join() print(m, 'main 2') >>> <__main__.multi object @ 0x000001e19015ccc0> main 1 >>> <__mp_main__.multi object @ 0x00000246b3614e10> loop >>> <__main__.multi object @ 0x000001e19015ccc0> main 2 because of that, value of x never updated in original class.
fortunately, there value object can use handles this. creates shared memory object can modified through processes
from multiprocessing import process, value class multi: def __init__(self): self.x = value('i', 20) def loop(self): in range(1, 100): self.x.value = if __name__ == '__main__': m = multi() p = process(target=m.loop) p.start() p.join() print(int(m.x.value)) >> 99
Comments
Post a Comment