How to correctly specify timeout in ThreadPoolExecutor (Python)?

Question

I have the following code where I am trying to call functions with different timeouts. It might happen that the first function times out but the second one could have been executed in the specified time.

import time
from concurrent.futures import ThreadPoolExecutor

def test1(a, b, c):
    time.sleep(5)
    d=a+b+c
    print(d)

def test2(a, b):
    time.sleep(5)
    d=a+b
    print(d)

with ThreadPoolExecutor(max_workers=1) as executor1:
    try:
        executor1.submit(test1, 1,2,3).result(timeout=1)
    except:
        executor1.shutdown(wait=False)
        print("Pass")

with ThreadPoolExecutor(max_workers=1) as executor2:
    try:
        executor2.submit(test2, 1,2).result(timeout=8)
    except:
        executor2.shutdown(wait=False)
        print("Pass-2")

Expected Output

Pass
3

Actual Output

Pass
6
3

What I'd like to have is stop the execution of first executor as soon as there is a timeout. And continue with the next executor.

score 0 · Answer 1 · answered Jan 27 '21 at 16:00

Finally, it is implemented using this link. The final code is shared below :-

import time
from concurrent.futures import ThreadPoolExecutor
import ctypes

def terminate_thread(thread):
    """Terminates a python thread from another thread.

    :param thread: a threading.Thread instance
    """
    if not thread.isAlive():
        return

    exc = ctypes.py_object(SystemExit)
    res = ctypes.pythonapi.PyThreadState_SetAsyncExc(
        ctypes.c_long(thread.ident), exc)
    if res == 0:
        raise ValueError("nonexistent thread id")
    elif res > 1:
        # """if it returns a number greater than one, you're in trouble,
        # and you should call it again with exc=NULL to revert the effect"""
        ctypes.pythonapi.PyThreadState_SetAsyncExc(thread.ident, None)
        raise SystemError("PyThreadState_SetAsyncExc failed")

def test1(a, b, c):
    time.sleep(5)
    d=a+b+c
    print(d)

def test2(a, b):
    time.sleep(5)
    d=a+b
    print(d)

with ThreadPoolExecutor(max_workers=1) as executor:
    try:
        executor.submit(test1, 1,2,3).result(timeout=1)
    except:
        executor.shutdown(wait=False)
        for t in executor._threads:
            terminate_thread(t)
        print("Pass")

with ThreadPoolExecutor(max_workers=1) as executor:
    try:
        executor.submit(test2, 1,2).result(timeout=8)
    except:
        executor.shutdown(wait=False)
        for t in executor._threads:
            terminate_thread(t)
        print("Pass-2")

How to correctly specify timeout in ThreadPoolExecutor (Python)?

1 Answers1