Get length of Queue in Python's multiprocessing library

Question

I have a multiprocessing.Manager object that contains a multiprocessing.Queue to manage all of the work that I want a group of processes to do. I would like to get the number of elements left in this queue and was wondering how to do this?

Python's inbuilt len() function does not work.

Answer 1

If the queue you are talking about is multiprocessing.Queue, try to use qsize() method for multiprocessing.Queue objects, but be careful:

qsize()

Return the approximate size of the queue. Because of multithreading/multiprocessing semantics, this number is not reliable.

Note that this may raise NotImplementedError on Unix platforms like Mac OS X where sem_getvalue() is not implemented.