Reuse Executor

This example highlights the loky API to reuse a ReusableProcessPool.

The factory get_reusable_executor provides an executor. As long as this executor is not in a broken state, it is reused for all the computation.

All the jobs were run in a process different from main process
All the computation where run in a single `ProcessPoolExecutor` with worker pid=185

import os
from loky import get_reusable_executor


def func_async(i):
    pid = os.getpid()
    return (2 * i, pid)


def test_1():
    executor = get_reusable_executor(max_workers=1)
    return executor.submit(func_async, 1)


def test_2():
    executor = get_reusable_executor(max_workers=1)
    return executor.submit(func_async, 2)


def test_3():
    executor = get_reusable_executor(max_workers=1)
    return executor.submit(func_async, 3)


f1 = test_1()
f2 = test_2()
f3 = test_3()

main_pid = os.getpid()
results = [f1.result(), f2.result(), f3.result()]

pids = [pid for _, pid in results]

for i, (val, pid) in enumerate(results):
    assert val == 2 * (i + 1)
    assert pid != main_pid
print("All the jobs were run in a process different from main process")

assert len(set(pids)) == 1
print(
    "All the computation where run in a single `ProcessPoolExecutor` with "
    f"worker pid={pids[0]}"
)