How to end all tasks in a ThreadPoolExecutor if one of them can throw an exception

Question

I have one task that I want to do:

def task(body):
    # some logic that which can throw an exception
    # if something goes wrong
    do_task(body) 

and the logic inside this task can throw an exception

And I have execute method with executor:

def execute():
    executor = ThreadPoolExecutor(max_workers=4)
    future1 = executor.submit(task, body1)
    future2 = executor.submit(task, body2)
    future3 = executor.submit(task, body3)
    future4 = executor.submit(task, body4)
    
    result1 = future1.result()
    result2 = future2.result()
    result3 = future3.result()
    result4 = future4.result()

And I want if at least one task crashes - do not wait for the completion of other tasks and stopped everything. How can I do this correctly?

Answer 1

To abandon waiting for other tasks when one raises, you can use concurrent.futures.wait() with the FIRST_EXCEPTION flag:

def execute():
    executor = ThreadPoolExecutor(max_workers=4)
    future1 = executor.submit(task, body1)
    future2 = executor.submit(task, body2)
    future3 = executor.submit(task, body3)
    future4 = executor.submit(task, body4)

    done, not_done = concurrent.futures.wait(
        [future1, future2, future3, future4],
        return_when=concurrent.futures.FIRST_EXCEPTION
    )
    if not_done:
        # at least one future has raised - you can return here
        # or propagate the exception
        #list(not_done)[0].result()  # re-raises exception here
        return  # ignores exception and returns

    result1 = future1.result()
    result2 = future2.result()
    result3 = future3.result()
    result4 = future4.result()
    ...

Note that the remaining tasks will still keep running in the background. There is no way to stop them forcibly.