CODEWITHSUNDEEP
pythonarraysmultithreadingglobalmultiprocess
Aphire
Aphire

Reputation: 1652

Python global array with multiprocessing

Please consider the following code:

from multiprocessing import Process
import time

myArray = []

def myThread():
    counter = 0
    global myArray
    while True:
        myArray.append(counter)
        time.sleep(1)

counterThread = Process(target=myThread,)
counterThread.start()

while True:
    if len(myArray) > 0:
        print "Success"
    else:
        print ":("
        print myArray   
    time.sleep(1)

I am unable to get my success message, and i'm not sure why, I keep receiving :( and my terminal printing an empty array. I thought making the array global would mean any changes made at myThread() level would be applied?

Upvotes: 1

Views: 566

Answers (1)

ego2dot0
ego2dot0

Reputation: 459

You are creating an second process, which has no access to data of the main process. You can use threading.Thread(target=myThread,), but you has to synchronize the access threading.Lock(), if you are using more than one thread.

You should terminate your thread, when you are finished and wait for the thread with athread.join().

See: https://docs.python.org/2/library/threading.html

Upvotes: 2

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