Custom Thread

creating custom thread

We can inherit Thread class and create our own implementation of run method.
We only need to implement __init__ and run method.
Then, we can use start, join and other methods as we did with thread class.

from threading import Thread

class MyThread(Thread):
    def __init__(self, num):
        self.num = num
        super().__init__() # calling the parent class constructor (required)

    def run(self):
        for i in range(10):
            print(f"I'm thread: {self.num} => {i}")

if __name__ == "__main__":
    my_t = []
    for i in range(5):
        curr_t = MyThread(i+1)
        my_t.append(curr_t)

    print("=== start all the threads ===")
    for t in my_t:
        t.start()

    for t in my_t:
        t.join()

    print("=== all threads finished ===")

Make custom daemon thread

to make the thread a daemon thread, we can set daemon=True in the constructor.

super().__init__(daemon=True)

Methods of Thread

start: This method starts the thread.
join(timeout=None): This method waits infinitely for the thread to finish.
join(timeout): This method waits for the thread to finish for the specified time. join() method always return None. So to check if the join() method completed bcoz task is over, or due to timeout, we can use is_alive() method.
If is_alive() returns True, then the thread is still running, and timeout has occurred (if join(timeout) is completed).