Multithreading

• Perform multiple tasks at the same time.
• It is good for when you wanna perform I/O tasks, e.g.:
  • Make HTTP calls.
  • Store something in DB.
• Without multithreading you cannot have these kind of codes:

But if you use the Thread class you can run function in a separate thread.

[!CAUTION]

Thread class used down below does not allow for actual parallelism. But if you want real parallelism you need to use multiprocessing.

[!CAUTION]

Here if we change the loop to while True, even if you hit enter it wont quit. The reason is simple, main thread has nothing else to run, but the other thread is still executing the worker function.

Though you can tell Python interpreter that a thread should be closed ASAP the main thread was closed:

# ...
thread = Thread(target=worker, daemon=True)
# ...

Passing Arguments to the Function

• args accepts a tuple.

def worker(some_arg: str):
    print(some_arg)
Thread(target=worker, args=("abc",))

[!TIP]

If you need to wait for the threads to finish their tasks and after that you wanna continue you need to use the thread.join() method.

• Example.