Multithreading while calling shell commands from python

Question

Suppose I am iteratively calling different bash commands with Python while my script is running. How would I do threading (or sleep) such that my Python script would not stall and stop? I tried using:

threading.Timer(5.0, self.func).start()

But maybe because my shell commands are complex the Python script/application stalls.

Example:

def func(self, command):
    cmd = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True)
    output, eff = cmd.communicate()
    return output

def __init__(self, parent=None):
    threading.Timer(5.0, self.func).start()
    command = "ifconfig"
    print self.func(command)

ps but I dont call "ifconfig" it is just an example

Answer 1

You're calling func twice. On the last line, you're calling it on the same thread you're standing. This is going to block until func returns.

Answer 2

You do not send command as parameter to your function while creating timer. I made a working example based on your code and here is how you run a timer with parameters. As @felipe-lema said, you are calling function twice and I did not change it in code although I did not understand the reason.

threading.Timer(interval, function, args=[], kwargs={})

#!/usr/bin/python2.7
import sys
import threading
import subprocess

class TestClass(object):

    def __init__(self, parent=None):
        command = "ifconfig"
        threading.Timer(5.0, self.func, (command,),).start()
        print self.func(command)

    def func(self, command):
        cmd = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True)
        output, eff = cmd.communicate()
        sys.stdout.write("In Thread "+threading.current_thread().name+"\n")
        sys.stdout.write(output)
        return output

TestClass()