check_proxy.py

import requests

with open('proxies.txt') as f:
    proxies = f.read().split('\n')
    """ or!
    proxies = f.readlines()
    proxies = [proxy.strip() for proxy in proxies]
    """

working_proxies = []

print(proxies)
for proxy in proxies:
    try:
        print(f'Using the proxy: {proxy}')
        r = requests.get(url='https://books.toscrape.com/', proxies={'https': proxy}, timeout=1)
        if r.status_code == 200:
            print('Proxy is working')
            working_proxies.append(proxy)
        else:
            print(r.status_code)
    except Exception as e:
        print(e)

with open('working_proxies.txt', 'w') as f:
    for proxy in working_proxies:
        f.write(proxy + '\n')

exampleCheckProxies.py

if __name__ == '__main__':

    import requests, threading, queue

    q = queue.Queue()
    valid_proxies = []

    with open('proxies.txt', 'r') as f:
        proxies = f.read().split('\n')
        for proxy in proxies:
            q.put(proxy)


    def check_proxies():
        global q
        while not q.empty():
            proxy = q.get()
            try:
                response = requests.get('http://ipinfo.io/json', proxies={'http': proxy, 'https': proxy})
            except:
                continue
            if response.status_code == 200:
                print(proxy)


    for _ in range(10):
        threading.Thread(target=check_proxies).start()