multithreading - Multi Threading python problem, not printing

Question

I am currently learning multithreading and learned about concurrent.futures and the threading pool executor, i tried to implement an example but for some reason it was not printing the multiple print orders. where did i go wrong?

import requests
import random
import string
import concurrent.futures

result = open(r"workingGhosts.txt","w")
length = 5
url ="https://ghostbin.co/paste/"

def get_random_string(length):
    letters = string.ascii_lowercase
    result_str = ''.join(random.choice(letters) for i in range(length))
    return result_str

times = int(input("how many times do you want to check?"))

list_urls=[]

counter = 0
for x in range(times):
    stringA = url + get_random_string(length)
    list_urls.append(stringA)

def lol(finalUrl):
    r = requests.get(finalUrl)
    counter= counter +1
    print("printing")
    if r.status_code != 404:
        result.write(finalUrl)


with concurrent.futures.ThreadPoolExecutor() as executor:
    executor.map(lol,list_urls)

Answer 1

I'ts not printing because there is an exception. these aren't shown to you unless you check for them yourself while using an executor
the exception you are getting is:

UnboundLocalError: local variable 'counter' referenced before assignment

because of this line

counter= counter +1

change lol like this:

def lol(finalUrl):
    global counter  # add this line
    r = requests.get(finalUrl)
    counter= counter +1
    print("printing")
    if r.status_code != 404:
        result.write(finalUrl)