How can i limit selenium browser count? [duplicate]

The following sample program creates a thread pool with only 2 threads for demo purposes and then scrapes 4 URLs to get their titles:

from multiprocessing.pool import ThreadPool
from bs4 import BeautifulSoup
from selenium import webdriver
import threading
import gc

class Driver:
    def __init__(self):
        options = webdriver.ChromeOptions()
        options.add_argument("--headless")
        # suppress logging:
        options.add_experimental_option('excludeSwitches', ['enable-logging'])
        self.driver = webdriver.Chrome(options=options)
        print('The driver was just created.')

    def __del__(self):
        self.driver.quit() # clean up driver when we are cleaned up
        print('The driver has terminated.')


threadLocal = threading.local()

def create_driver():
    the_driver = getattr(threadLocal, 'the_driver', None)
    if the_driver is None:
        the_driver = Driver()
        setattr(threadLocal, 'the_driver', the_driver)
    return the_driver.driver


def get_title(url):
    driver = create_driver()
    driver.get(url)
    source = BeautifulSoup(driver.page_source, "lxml")
    title = source.select_one("title").text
    print(f"{url}: '{title}'")

# just 2 threads in our pool for demo purposes:
with ThreadPool(2) as pool:
    urls = [
        'https://www.google.com',
        'https://www.microsoft.com',
        'https://www.ibm.com',
        'https://www.yahoo.com'
    ]
    pool.map(get_title, urls)
    # must be done before terminate is explicitly or implicitly called on the pool:
    del threadLocal
    gc.collect()
# pool.terminate() is called at exit of with block

Prints:

The driver was just created.
The driver was just created.
https://www.google.com: 'Google'
https://www.microsoft.com: 'Microsoft - Official Home Page'
https://www.ibm.com: 'IBM - United States'
https://www.yahoo.com: 'Yahoo'
The driver has terminated.
The driver has terminated.