Launch another python command without waiting for a return.

Launch another python command without waiting for a return. - Printable Version

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Launch another python command without waiting for a return. - SpongeB0B - Jun-15-2020

Hi everyone,

Is it possible to launch a python command without waiting for a return ? and therefore start the next command without waiting the previous one to finish ?

I searched and asked also on StackOverflow but so far I didn't found what I was looking for...

something that look promising might be the

concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor

as seen here -> https://stackoverflow.com/a/60832288/11943028

But this example is focus on results that I don't need. any ideas ?

Thank you.

RE: Launch another python command without waiting for a return. - Gribouillis - Jun-15-2020

SpongeBob Wrote:but so far I didn't found what I was looking for...

It is quite unclear what you are looking for. If you want to start function spam() and do something else while spam() is running, you can simply start a thread that runs spam(). If you want to use a ThreadPoolExecutor to start the thread, why not? Why wouldn't this suit your needs? Have you tried anything? Post your code!

RE: Launch another python command without waiting for a return. - SpongeB0B - Jun-15-2020

Merci @Gribouillis ;)

Quote: If you want to start function spam() and do something else while spam() is running,

Yes it's what I would like to achieve.
But it not need to be constrain for functions only.
and a solution where the return of that function / code is not mandatory.

Because in all the example that I could find I see always liked to a return.

I was thinking to use ThreadPoolExecutor or ProcessPoolExecutor (depending if it's CPU or IO usage)
but I don't find a good document/tutorial where I could use those.

If you have any example that will be appreciate.

Thank for your help.

RE: Launch another python command without waiting for a return. - Gribouillis - Jun-15-2020

SpongeBob Wrote:If you have any example that will be appreciate.

You could perhaps check the Pymotw3 about concurrent.futures

RE: Launch another python command without waiting for a return. - nilamo - Jun-15-2020

The easy way would be to run it in a thread:

import threading

def do_something_and_move_on():
    pass

worker = threading.Thread(target=do_something_and_move_on)
worker.start()

# now do other things while it runs...

# then join the worker, to make sure it's done before the script ends
worker.join()

The more complicated answer would be to write your code using async/await, and let the asyncio library handle it for you. But that's harder to do if you already have code that you don't want to mess with.

RE: Launch another python command without waiting for a return. - SpongeB0B - Jun-16-2020

Thank you very much @nilamo !

I like simple code to demonstrate how it work.
After the worker.join() Can I retrieve a return value from the worker ?

@all
What is the main difference between those two modules ?
threading
concurrent

RE: Launch another python command without waiting for a return. - SpongeB0B - Jun-18-2020

(Jun-15-2020, 10:40 PM)nilamo Wrote:
import threading
....

Nilamo, by any chance did you have a simple example like this one but with

from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor

?

Because it really easy to switch thread/Process execution with this module. Thanks.

RE: Launch another python command without waiting for a return. - Gribouillis - Jun-18-2020

There are 9 simple examples like this one on the pymotw3 page I linked above...

RE: Launch another python command without waiting for a return. - SpongeB0B - Jun-18-2020

I tried this

import pyttsx3
from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor

def talk(txt):
    engine = pyttsx3.init()
    engine.say(txt)
    engine.runAndWait()
    engine.stop()
    return 'done'


executor = ThreadPoolExecutor(max_workers=20) 
future = executor.submit(talk('This will be, a long text for testing purpose.'))
print('This text should appear before or during the TTS')
print(future.result())

At the moment 'This text should appear before or during the TTS' only appear once the tts engine is finished :/

and I have a bunch of error on the last line (print(future.result()))

Thanks.

RE: Launch another python command without waiting for a return. - Gribouillis - Jun-18-2020

I think it should be

future = executor.submit(talk, 'This will be, a long text for testing purpose.')

You don't call the function. Just pass the function and its arguments to submit.