who runs done_callback function?

[qiankunli]

for example

caller thread:
           with ProcessPool(max_workers=xx) as pool:
              future = pool.schedule(task_function, xx, timeout=xx)
              future.add_done_callback(done_callback_function)
           ...

who runs done_callback_function？caller thread or process which runs the task_function?

[noxdafox]

Hello,

the callback is executed by a thread within the Pool itself once results have been delivered back to the main process. Hence, its execution happens on the process which has been scheduling the task_function.

The same implementation as concurrent.futures.ProcessPoolExecutor and multiprocessing.Pool.