How to create a new thread in Python

Threads in python are an entity within a process that can be scheduled for execution. In simpler words, a thread is a computation process that is to be performed by a computer. It is a sequence of such instructions within a program that can be executed independently of other codes.

In Python, there are two ways to create a new Thread. In this article, we will also be making use of the threading module in Python. Below is a detailed list of those processes:

1. Creating python threads using class

Below has a coding example followed by the code explanation for creating new threads using class in python.  

# import the threading module
import threading 

class thread(threading.Thread): 
    def __init__(self, thread_name, thread_ID): 
        threading.Thread.__init__(self) 
        self.thread_name = thread_name 
        self.thread_ID = thread_ID 

        # helper function to execute the threads
    def run(self): 
        print(str(self.thread_name) +" "+ str(self.thread_ID)); 

thread1 = thread("GFG", 1000) 
thread2 = thread("GeeksforGeeks", 2000); 

thread1.start() 
thread2.start() 

print("Exit") 

Output: 

GFG 1000
GeeksforGeeks 2000
Exit

Now let's look into what we did up there in the code.  

1. We created a sub-class of the thread class.
2. Then we override the __init__ function of the thread class.
3. Then we override the run method to define the behavior of the thread.
4. The start() method starts a Python thread. 

2. Creating python threads using function

The below code shows the creation of new thread using a function:  

from threading import Thread
from time import sleep

# function to create threads
def threaded_function(arg):
    for i in range(arg):
        print("running")
        
        # wait 1 sec in between each thread
        sleep(1)


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

Output: 

running
running
running
running
running
running
running
running
running
running
thread finished...exiting

So what we did in the above code, 

1. We defined a function to create a thread.
2. Then we used the threading module to create a thread that invoked the function as its target.
3. Then we used start() method to start the Python thread.