Breakpoints don't work in threads created after debugpy.listen() is called #1963

# multithread_debugging.py

import sys
import threading
from queue import Queue

import debugpy

threads: list[threading.Thread] = []
queues: list[Queue] = []

N_THREADS = 10
POISON_PILL = -1


def handler(q: Queue):
    while True:
        item = q.get()
        print(threading.current_thread(), item)
        if item == POISON_PILL:
            print(threading.current_thread(), "exiting")
            return


def send(i: int, item):
    queues[i].put(item)


def end(i: int, *, wait=False):
    send(i, POISON_PILL)
    if wait:
        threads[i].join()


def end_all():
    for i in range(N_THREADS):
        end(i)
    for t in threads:
        t.join()
    print("all done")


if __name__ == "__main__":
    start_listener_at_index = 0
    if len(sys.argv) >= 2:
        start_listener_at_index = int(sys.argv[1])

    for i in range(10):
        q = Queue()
        t = threading.Thread(target=handler, args=[q])
        threads.append(t)
        queues.append(q)

    for i, t in enumerate(threads):
        if i == start_listener_at_index:
            print(f"starting debug listener before thread {i} starts")
            debugpy.listen(("0.0.0.0", 5680))
        t.start()