import subprocess
from threading import Thread
import sys
from time import time, sleep

def thread_proc(id, path, n, on_exit, state):
    p = subprocess.Popen(["python.exe", path, n],
                      stdout = subprocess.PIPE,
                      stderr = subprocess.STDOUT,
                      universal_newlines=True)

    for l in p.stdout:
        print(id, ": Child output:", l, end='')

    p.communicate()
    print(id, ": Child exited")
    on_exit(state)

def on_0_exit(state):
    state["process_0_exit_time"] = time()

def on_1_exit(state):
    if "process_0_exit_time" in state and \
       time() - state["process_0_exit_time"] > 2:
        print("CORRECT: Thread 0 returned immediately after the child process 0 exited")
    else:
        print("ERROR: Thread 0 returned after two child processes exited")

def test_main():
    state = dict()
    thread0 = Thread(target=thread_proc,
                     args=(0, sys.argv[0], "5", on_0_exit, state))
    thread1 = Thread(target=thread_proc,
                     args=(1, sys.argv[0], "10", on_1_exit, state))
    thread0.start()
    # uncomment the following line to get expected result
    # sleep(1)
    thread1.start()
    thread0.join()
    thread1.join()

def unbuffered_print(*args, **kwargs):
    print(*args, **kwargs)
    sys.stdout.flush()

def test_child():
    unbuffered_print("Child started")
    unbuffered_print("Waiting for", sys.argv[1], "seconds")
    sleep(int(sys.argv[1]))
    unbuffered_print("Child exiting")



if __name__ == "__main__":
    if len(sys.argv) == 1:
        test_main()
    else:
        test_child()