This is mostly useful for when you've got a large number of threads and want to try and identify what threadpool is going nuts.

A workaround for this on 3.5 and older versions is probably to do:

initialization:

num_q = queue.Queue()
map(num_q.put, range(max_workers))

Then schedule max_workers identical tasks:

def task():
  threading.current_thread().name = '%s_%d' % (your_prefix, num_q.get())
  num_q.task_done()
  num_q.join()  # block so that this thread cannot take a new thread naming task until all other tasks are complete.  guaranteeing we are executed once per max_workers threads.

New changeset 1002a1bdc5b1 by Gregory P. Smith in branch 'default':
Issue #27664: Add to concurrent.futures.thread.ThreadPoolExecutor()
https://hg.python.org/cpython/rev/1002a1bdc5b1

cleaned up a bit with documentation added and submitted.  thanks.  ThreadPoolExecutor threads now have a default name as well, because why not.