Question

I have a thread which extends Thread. The code looks a little like this;

class MyThread(Thread):
    def run(self):
        # Do stuff

my_threads = []
while has_jobs() and len(my_threads) < 5:
    new_thread = MyThread(next_job_details())
    new_thread.run()
    my_threads.append(new_thread)

for my_thread in my_threads
    my_thread.join()
    # Do stuff

So here in my pseudo code I check to see if there is any jobs (like a db etc) and if there is some jobs, and if there is less than 5 threads running, create new threads.

So from here, I then check over my threads and this is where I get stuck, I can use .join() but my understanding is that – this then waits until it’s finished so if the first thread it checks is still in progress, it then waits till it’s done – even if the other threads are finished….

so is there a way to check if a thread is done, then remove it if so?

eg

for my_thread in my_threads:
    if my_thread.done():
        # process results
        del (my_threads[my_thread]) ?? will that work...

Answer 1

As TokenMacGuy says, you should use thread.is_alive() to check if a thread is still running. To remove no longer running threads from your list you can use a list comprehension:

for t in my_threads:
    if not t.is_alive():
        # get results from thread
        t.handled = True
my_threads = [t for t in my_threads if not t.handled]

This avoids the problem of removing items from a list while iterating over it.