Python user input in child process

Question

I'm trying to create a child process that can take input through raw_input() or input(), but I'm getting an end of liner error EOFError: EOF when asking for input.

I'm doing this to experiment with multiprocessing in python, and I remember this easily working in C. Is there a workaround without using pipes or queues from the main process to it's child ? I'd really like the child to deal with user input.

def child():
    print 'test' 
    message = raw_input() #this is where this process fails
    print message

def main():
    p =  Process(target = child)
    p.start()
    p.join()

if __name__ == '__main__':
    main()

I wrote some test code that hopefully shows what I'm trying to achieve.

Community · Accepted Answer · 2017-05-23 11:43:58Z

4

My answer is taken from here: Is there any way to pass 'stdin' as an argument to another process in python?

I have modified your example and it seems to work:

from multiprocessing.process import Process
import sys
import os

def child(newstdin):
    sys.stdin = newstdin
    print 'test' 
    message = raw_input() #this is where this process doesn't fail anymore
    print message

def main():
    newstdin = os.fdopen(os.dup(sys.stdin.fileno()))
    p =  Process(target = child, args=(newstdin,))
    p.start()
    p.join()

if __name__ == '__main__':
    main()

edited May 23, 2017 at 11:43

CommunityBot

11 silver badge

answered Dec 12, 2012 at 9:11

ZalewaPL

1,1501 gold badge6 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Alexander Pope Over a year ago

does this work on your end ? I get ValueError: I/O operation on closed file

ZalewaPL Over a year ago

Yes it does. Maybe the behavior is OS dependant. What OS are you on? I'm on Linux.

Alexander Pope Over a year ago

Windows 8, i guess this is problem

Alexander Pope Over a year ago

That works, somewhat, but the child now can't exit from raw_input(), and the whole script strangely exists after 3~4 seconds, and none of the print statements work.

Alexander Pope Over a year ago

I'm not building a large application here, I was trying to do this in order to better grasp python and it's multiprocessing library. Thank you for your time and advice though !

|

Collectives™ on Stack Overflow

Python user input in child process

1 Answer 1

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related