Python Thread running asynchronously

Question

I am trying to run the below code expecting it to run asynchronously.

import threading
import time


def mock_app(widgets=None, filters=None):
    print('Mock app called')
    task = threading.Thread(target=mock_app_handler(), args=())
    task.start()
    print('Thread spawned')
    return "success"


def mock_app_handler():
    # do something
    print('doing something')
    time.sleep(2)
    print('done something')


print(mock_app())

But, the code is executing synchronously. I am getting the below result.

Mock app called
doing something
done something
Thread spawned
success

Why is this happening? Am I missing something?

UPDATE: I tried setting task.daemon = True. That didn't work either.

task = threading.Thread(target=mock_app_handler) # don't call the function there, instead pass the function object. Also you don't need the args there, since the function doesn't take any arguments — han solo
– han solo, Commented May 29, 2021 at 18:18
@hansolo Thanks. My bad. Didn't realize it until now. Worked now. — brainless
– brainless, Commented May 29, 2021 at 18:20

han solo · Accepted Answer · 2021-05-29 18:54:26Z

2

The problem was, you were calling the function mock_app_handler instead of passing the function object. The target in threading.Thread expects a callable. So

Instead of

task = threading.Thread(target=mock_app_handler(), args=())

Use

task = threading.Thread(target=mock_app_handler)

Also you don't need to pass the empty args, since the function mock_app_handler doesn't need any args.

answered May 29, 2021 at 18:54

han solo

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1 Comment

brainless Over a year ago

My code is a stripped-down version of the actual code. The actual code has args to be passed. Thanks.

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