Ping multiple sites via Python

Here is a simple script that I am using to ping 50 sites at a time and check if they are up or not. If not, save the down time with error in MongoDB.

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from urllib.request import urlopen, Request
from threading import Thread
from time import sleep, time
import datetime
import queue
import pymongo

''' A Simple script to  ping multiple sites at a time
and capture the down sites
'''
__author__ = "Aamir khan"
__version__ = 1.1

_MAX_CONNECTIONS = 50
counter = 0
downsites = []
now = datetime.datetime.utcnow  # time stamp

# DO NOT ON BOTH AT THE SAME TIME
_DEBUG = False
_MONITOR = True


def getcollection(db='websites', colname='website_urls'):
    return pymongo.MongoClient().get_database(db).get_collection(colname)


# to save downsites in db
ds = getcollection(colname="downsites")

# fetch urls from db    
if _DEBUG:
    print("Fetching Urls")
    urls = getcollection().find()
    print("%d Urls Fetched" % urls.count())
    print("pulling urls to the queue")
    q = queue.Queue(urls.count())
    for url in urls:
        url = url['url']
        q.put(url)
    print("pulled urls to the queue")
    print("The size of the Queue is %d" % q.qsize())
else:
    urls = getcollection().find()
    q = queue.Queue(urls.count())
    for url in urls:
        url = url['url']
        q.put(url)

del urls


def inc_counter():
    global counter
    # lock.acquire()
    counter += 1
    # lock.release()


def monitor():
    total = q.qsize()
    if total > 0:
        while counter < total:
            print("%d Request sent" % counter)
            sleep(1)
        print("Total {}/{} Request Sent".format(counter, total))
        assert counter == total


def ping(uri):
    req = Request(uri, headers={
        "User-Agent": ("Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:51.0)"
                       " Gecko/20100101 Firefox/51.0")
    })
    req.get_method = lambda: 'HEAD'

    try:
        with urlopen(req) as r:
            res = r.getcode(), uri, now()
    except Exception as e:
        res = str(e), uri, now()
    finally:
        if _DEBUG:
            err, uri, last_check = res
            print("Requesting = ", uri, "Request Method = ", req.get_method(),
                  "\nstatus = ", err, "time", last_check)
            print("-----" * 10)
        if _MONITOR:
            inc_counter()
            sleep(1)
        sleep(0.5)  # sleep a while to release the workload from cpu
    return res


def process(url):
    err, uri, last_check = ping(url)
    if err != 200:
        ds.insert_one({"Error": err.strip('<>'),
                       "url": uri, "last_checked": last_check})


def worker():
    while True:
        url = q.get()
        if url is None:
            break
        process(url)
        q.task_done()


if __name__ == '__main__':
    workers = []

    if _MONITOR:
        Thread(target=monitor).start()  # start monitoring reqest/sec
        start_time = time()

    for i in range(_MAX_CONNECTIONS):
        t = Thread(target=worker)
        t.start()
        workers.append(t)

    # block until all tasks are done
    q.join()

    # poision kill
    for i in range(_MAX_CONNECTIONS):
        q.put(None)

    # wait for all the threads to join
    for w in workers:
        w.join()

    if _MONITOR:
        print("Time taken %f (sec)" % (time() - start_time))

Questions:

• Can I make use of better threading techniques?
• Can I eliminate the duplication of code while _DEBUG is on line 35 to 54?
• I would love/prefer to see a functional version of this program.
• How can I improve the performance? (my target is to ping 1000000 sites under an hour)