Question

just as the sample code shows:

for temp in range(0, 10):
       thread = threading.Thread(target = current_post.post)
       thread.start()
       threads.append(thread)

for current in range(10):
        threads[current].join()

the code is just a part of a python file, but it stands for most circumstances: i should execute join() after start() in multithreading. i have been confusing by it for a few days. as we all know, when we execute thread.start(), a new thread then starts, python runs through different threads automatically, thats all we need. if so, why should i add thread.join() after start()? join() means waiting until the current thread finished IMO. but does it means a kind of single-thread? i have to wait each thread to finish their tasks, its not multithreading! join() only means executing the specified function one by one IMO. cannot start() finish the multi-threading perfectly? why should i add join() function to let them finish one by one? thx for any help 🙂

Answer 1

You do it in order to be sure that your threads have actually finished (and do not become, for example, zombie processes, after your main thread exits).

However, you don’t have to do it right after starting the threads. You can do it at the very end of your process.