Because of the way gevent works, you can take a blocking script, and with very few modifications, make it async. Let's take the original stdlib one, and convert it to gevent:
``` import re import time
import gevent from gevent import monkey
monkey.patch_all() # THIS MUST BE DONE BEFORE IMPORTING URLLIB
from urllib.request import Request, urlopen
urls = [ "https://www.bitecode.dev/p/relieving-your-python-packaging-pain", "https://www.bitecode.dev/p/hype-cycles", "https://www.bitecode.dev/p/why-not-tell-people-to-simply-use", "https://www.bitecode.dev/p/nobody-ever-paid-me-for-code", "https://www.bitecode.dev/p/python-cocktail-mix-a-context-manager", "https://www.bitecode.dev/p/the-costly-mistake-so-many-makes", "https://www.bitecode.dev/p/the-weirdest-python-keyword", ]
title_pattern = re.compile(r"<title[^>]>(.?)</title>", re.IGNORECASE)
user_agent = ( "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/116.0" )
We move the fetching into a function so we can isolate it into a green thread
def fetch_url(url): start_time = time.time()
headers = {"User-Agent": user_agent}
with urlopen(Request(url, headers=headers)) as response:
html_content = response.read().decode("utf-8")
match = title_pattern.search(html_content)
title = match.group(1) if match else "Unknown"
print(f"URL: {url}\nTitle: {title}")
end_time = time.time()
elapsed_time = end_time - start_time
print(f"Time taken: {elapsed_time:.4f} seconds\n")
def main(): global_start_time = time.time()
# Here is where we convert synchronous calls into async ones
greenlets = [gevent.spawn(fetch_url, url) for url in urls]
gevent.joinall(greenlets)
global_end_time = time.time()
global_elapsed_time = global_end_time - global_start_time
print(f"Total time taken: {global_elapsed_time:.4f} seconds")
main() ```
No async, no await. No special lib except for gevent. In fact it would work with the requests lib just as well. Very few modifications are needed, for a net perf gain.
The only danger is if you call gevent.monkey.patch_all() too late. You get a cryptic error that crashes your program.