writing large amount of data to stdin

Question

I am writing a large amount of data to stdin.

How do i ensure that it is not blocking?

p=subprocess.Popen([path],stdout=subprocess.PIPE,stdin=subpr         


        

Answer 1

To avoid the deadlock in a portable way, write to the child in a separate thread:

#!/usr/bin/env python
from subprocess import Popen, PIPE
from threading import Thread

def pump_input(pipe, lines):
    with pipe:
        for line in lines:
            pipe.write(line)

p = Popen(path, stdin=PIPE, stdout=PIPE, bufsize=1)
Thread(target=pump_input, args=[p.stdin, lines]).start()
with p.stdout:
    for line in iter(p.stdout.readline, b''): # read output
        print line,
p.wait()

See Python: read streaming input from subprocess.communicate()