Find all usernames that are (potentially available) to use on GitHub

github_username_test.py

from queue import Queue
from threading import Thread, Lock
from itertools import product
from string import ascii_lowercase
import requests

usrs = [''.join(i) for i in product(ascii_lowercase + '-', repeat = 3)]
usrs = [x for x in usrs if (not x.startswith('-')) and (not x.endswith('-'))]

class Worker(Thread):
    def __init__(self, tasks):
        """
        :param tasks: A queue containing the tasks for the worker instance.
        :type tasks: queue.Queue instance

        """
        Thread.__init__(self)
        self.tasks = tasks
        self.daemon = True
        self.start()

    def run(self):
        while True:
            func, args, kwargs = self.tasks.get()

            while True:
                try:
                    func(*args, **kwargs)
                except Exception as e:
                    print(e)
                    continue
                else:
                    self.tasks.task_done()
                    break

class ThreadPool:
    def __init__(self, thread_count):
        self.tasks = Queue(thread_count)
        # underscore because unused counter variable
        for _ in range(thread_count):
            Worker(self.tasks)

    def add_task(self, func, *args, **kwargs):
        """ Add a new task to the queue. """
        self.tasks.put((func, args, kwargs))

    def map(self, func, args_list):
        """ Add a list of extant tasks to queue. """
        for args in args_list:
            self.add_task(func, args)

    def wait_completion(self):
        """ Blocks until all tasks in queue have been processed. """
        self.tasks.join()

# thread pool with n Workers
pool = ThreadPool(15)
lock = Lock()

def check_available(username):
    if requests.get('https://github.com/{}'.format(username)).status_code == 404:
        print(username + ' is available.')

for username in usrs:
    pool.add_task(check_available, username)

pool.wait_completion()