more thread question

[nilamo]

.join() will wait until that thread is finished.  If you don't call it, there won't be any errors or anything, but the main program might finish before the threads are done, so if there was some processing or output they were doing, you might not see it, because they maybe will be killed when python exits before they complete.

That's one of the tricky things about working with threads... sometimes it'll seem like it's working fine, and sometimes it won't, even though you've made no changes to your code.