This content originally appeared on flaviocopes.com and was authored by flaviocopes.com
A Python application runs on a single thread, unless you explicitly enable multithreading.
Why is multithreading useful? Code in Python is ran in sequence, one instruction after another.
If you define a function that sleeps 3 seconds and then prints something, like this:
import time
def greet():
time.sleep(3)
print('hello')
greet()
print('world')The world string is printed after 3 seconds, because we call time.sleep(3) inside the greet() function.
This is just a silly example, but imagine processing an image, getting a resource from the network, or writing a big file to disk. Anything that can take a lot of time.
With multithreading we can run the function that takes a lot of time into a separate thread, and go on with our program in the meantime.
The threading standard library module helps with implementing multithreading. You import Thread from it:
from threading import ThreadThen we pass the function we must execute as the target argument to the Thread() function, getting a thread object:
t = Thread(target=greet)then we call its start() method to start the thread:
t.start()Try running this code:
from threading import Thread
import time
def greet():
time.sleep(3)
print('hello')
t = Thread(target=greet)
t.start()
print('world')You will now see world printed 3 seconds before hello shows up in the console.
The program does not end until the thread (or all the threads it started) end, unless you start a thread as a deamon.
Those are the basics of multithreading. This is complex, and can lead to the introduction of bugs if not done well.
This content originally appeared on flaviocopes.com and was authored by flaviocopes.com
flaviocopes.com | Sciencx (2021-02-25T05:00:00+00:00) Introduction to multithreading in Python. Retrieved from https://www.scien.cx/2021/02/25/introduction-to-multithreading-in-python/
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