How can I get return value from multiple processes in python?

Question

I want to get return values from multiple processes initialised in one function and started in another function.

 import multiprocessing
 import time

 class Auto:

    def __init__(self):
        self.msf = 0

    def auto(self, return_dict, i):
        # print "hello"
        return_dict["hello"] = "hello{}".format(i)

    def msf1(self):
        man = multiprocessing.Manager()
        self.return_dict = man.dict()
        self.a= multiprocessing.Process(target=self.auto, args=(self.return_dict, 1, ))
        self.b= multiprocessing.Process(target=self.auto, args=(self.return_dict, 1, ))
        self.c= multiprocessing.Process(target=self.auto, args=(self.return_dict, 1, ))

    def msf2(self):
        self.a.start()
        self.b.start()
        self.c.start()

        return self.return_dict.values()

You could return them via a queue

MyNameIsCaleb
– MyNameIsCaleb

2019-05-22 13:08:55 +00:00
Commented May 22, 2019 at 13:08 — MyNameIsCaleb
– MyNameIsCaleb, Commented May 22, 2019 at 13:08
Can you illustrate with code?

cjosy
– cjosy

2019-05-23 07:07:10 +00:00
Commented May 23, 2019 at 7:07 — cjosy
– cjosy, Commented May 23, 2019 at 7:07

MyNameIsCaleb · Accepted Answer · 2019-05-24 13:53:54Z

1

You can use a Queue() to collect items from multiple processes. [docs]

Here is a very simple example of how it can work. See this part of the docs for a more in depth example of how it works.

def number(done_queue):
    done_queue.put(5)

done_queue = multiprocessing.Queue()
x = Process(target=number, args=(done_queue))
x.start()
x.join()
y = [i for i in done_queue]
print(y)

edited May 24, 2019 at 13:53

user10417531

answered May 24, 2019 at 12:26

MyNameIsCaleb

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