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' 

7 Answers

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.

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

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() 

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

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?

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 = [' ' ' ' ' # 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() 

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()