Python Multiprocessing：AssertionError：当多个进程在循环中产生时，只能加入一个启动的进程错误

Question

I have spawned multiple process using for loop and appended each process into an array after starting it.

for param in multiples_100:
    p = Process(target=calculate, args=(param,))
    processes.append(p)
    p.start()
p = Process(target=calculate, args=(200,))
processes.append(p)
for p in processes:
    p.join()

when I try to join all processes It's throwing AssertionError: can only join a started process

Answer 1

You do not start the final process outside the loop.

for param in multiples_100:
    p = Process(target=calculate, args=(param,))
    processes.append(p)
    p.start()
p = Process(target=calculate, args=(200,))
p.start()
processes.append(p)
for p in processes:
    p.join()

should fix it.