Communicating with subprocess (via Popen)

I'm using this code to test communication with a Python 3 wrapper around a Python 3 only library.

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#client.py:   test client for communicating with wrapper.py

from subprocess import Popen, PIPE
from threading import Thread
from time import sleep

def read_it():
    print(u"read_it thread running")
    while True:
   
        for msg in process.stdout:
            print(u"subprocess output: {}".format(msg.rstrip()))
       

print(u"subprocess starting")
process = Popen(['/usr/bin/python3', './wrapper.py', 'arg1, 'arg2'],
                                stdin=PIPE, stdout=PIPE, close_fds=True, bufsize=1, universal_newlines=True)
print(u"subprocess running: {}".format(process.pid))
                               
thread = Thread(target=read_it)
thread.daemon = True
thread.start()

sleep(5.0)  # wait for initial output from subprocess


When this run using Python3, it works as expected:

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% /usr/bin/python3 --version
Python 3.8.2

% /usr/bin/python3 ./client.py
subprocess starting
subprocess running: 24458
read_it thread running
subprocess output: {"msg": "status", "status": "Login Complete"}


But not when running using Python2:

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% /usr/bin/python --version
Python 2.7.16

% /usr/bin/python ./client.py
subprocess starting
subprocess running: 24466
read_it thread running


Both processes are definitely running, I'm checking that in another Terminal window.

Any ideas?

[matt (support)]

In your for loop try using readline().

Hmm. Changing it like this works:

Code: Select all

def read_it():
    print(u"read_it thread running")
    while True:
   
        msg = process.stdout.readline()
        print(u"subprocess output: {}".format(msg.rstrip()))       


Now to try it in the actual plugin...