Creating Threads in python

I have a script and I want one function to run at the same time as the other.

The example code I have looked at:

import threading

def MyThread (threading.thread):
    # doing something........

def MyThread2 (threading.thread):
    # doing something........

MyThread().start()
MyThread2().start()

I am having trouble getting this working. I would prefer to get this going using a threaded function rather than a class.

This is the working script:

from threading import Thread

class myClass():

    def help(self):
        os.system('./ssh.py')

    def nope(self):
        a = [1,2,3,4,5,6,67,78]
        for i in a:
            print i
            sleep(1)


if __name__ == "__main__":
    Yep = myClass()
    thread = Thread(target = Yep.help)
    thread2 = Thread(target = Yep.nope)
    thread.start()
    thread2.start()
    thread.join()
    print 'Finished'

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

You don’t need to use a subclass of Thread to make this work – take a look at the simple example I’m posting below to see how:

from threading import Thread
from time import sleep

def threaded_function(arg):
    for i in range(arg):
        print("running")
        sleep(1)


if __name__ == "__main__":
    thread = Thread(target = threaded_function, args = (10, ))
    thread.start()
    thread.join()
    print("thread finished...exiting")

Here I show how to use the threading module to create a thread which invokes a normal function as its target. You can see how I can pass whatever arguments I need to it in the thread constructor.

Method 2

There are a few problems with your code:

def MyThread ( threading.thread ):

• You can’t subclass with a function; only with a class
• If you were going to use a subclass you’d want threading.Thread, not threading.thread

If you really want to do this with only functions, you have two options:

With threading:

import threading
def MyThread1():
    pass
def MyThread2():
    pass

t1 = threading.Thread(target=MyThread1, args=[])
t2 = threading.Thread(target=MyThread2, args=[])
t1.start()
t2.start()

With thread:

import thread
def MyThread1():
    pass
def MyThread2():
    pass

thread.start_new_thread(MyThread1, ())
thread.start_new_thread(MyThread2, ())

Doc for thread.start_new_thread

Method 3

I tried to add another join(), and it seems worked. Here is code

from threading import Thread
from time import sleep

def function01(arg,name):
    for i in range(arg):
        print(name,'i---->',i,'n')
        print (name,"arg---->",arg,'n')
        sleep(1)

def test01():
    thread1 = Thread(target = function01, args = (10,'thread1', ))
    thread1.start()
    thread2 = Thread(target = function01, args = (10,'thread2', ))
    thread2.start()
    thread1.join()
    thread2.join()
    print ("thread finished...exiting")

test01()

Method 4

You can use the target argument in the Thread constructor to directly pass in a function that gets called instead of run.

Method 5

Did you override the run() method? If you overrided __init__, did you make sure to call the base threading.Thread.__init__()?

After starting the two threads, does the main thread continue to do work indefinitely/block/join on the child threads so that main thread execution does not end before the child threads complete their tasks?

And finally, are you getting any unhandled exceptions?

Method 6

Python 3 has the facility of Launching parallel tasks. This makes our work easier.

It has for thread pooling and Process pooling.

The following gives an insight:

ThreadPoolExecutor Example

import concurrent.futures
import urllib.request

URLS = ['http://www.foxnews.com/',
        'http://www.cnn.com/',
        'http://europe.wsj.com/',
        'http://www.bbc.co.uk/',
        'http://some-made-up-domain.com/']

# Retrieve a single page and report the URL and contents
def load_url(url, timeout):
    with urllib.request.urlopen(url, timeout=timeout) as conn:
        return conn.read()

# We can use a with statement to ensure threads are cleaned up promptly
with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
    # Start the load operations and mark each future with its URL
    future_to_url = {executor.submit(load_url, url, 60): url for url in URLS}
    for future in concurrent.futures.as_completed(future_to_url):
        url = future_to_url[future]
        try:
            data = future.result()
        except Exception as exc:
            print('%r generated an exception: %s' % (url, exc))
        else:
            print('%r page is %d bytes' % (url, len(data)))

Another Example

import concurrent.futures
import math

PRIMES = [
    112272535095293,
    112582705942171,
    112272535095293,
    115280095190773,
    115797848077099,
    1099726899285419]

def is_prime(n):
    if n % 2 == 0:
        return False

    sqrt_n = int(math.floor(math.sqrt(n)))
    for i in range(3, sqrt_n + 1, 2):
        if n % i == 0:
            return False
    return True

def main():
    with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
        for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
            print('%d is prime: %s' % (number, prime))

if __name__ == '__main__':
    main()

Method 7

the simple way to implement multithread process using threading

code snippet for the same

import threading

#function which takes some time to process 
def say(i):
    time.sleep(1)
    print(i)

threads = []
for i in range(10):
    
    thread = threading.Thread(target=say, args=(i,))

    thread.start()
    threads.append(thread)

#wait for all threads to complete before main program exits 
for thread in threads:
    thread.join()

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0