gevent example

dns_mass_resolve.py

#!/usr/bin/env python
"""Resolve hostnames concurrently, exit after 60 seconds.

Under the hood, this might use an asynchronous resolver based on
c-ares (the default) or thread-pool-based resolver.

You can choose between resolvers using GEVENT_RESOLVER environment
variable. To enable threading resolver:

    GEVENT_RESOLVER=thread python dns_mass_resolve.py
"""
import sys
import gevent
from gevent import socket
from gevent.pool import Pool

N = 1000
# limit ourselves to max 100 simultaneous outstanding requests
pool = Pool(100)
finished = 0


def job(url):
    global finished
    try:
        try:
            ip = socket.gethostbyname(url)
            print('%s = %s' % (url, ip))
        except socket.gaierror:
            ex = sys.exc_info()[1]
            print('%s failed with %s' % (url, ex))
    finally:
        finished += 1

with gevent.Timeout(60, False):
    for x in xrange(10, 10 + N):
        print(pool.full())
        pool.spawn(job, '%s.com' % x)
    pool.join()

print('finished within 60 seconds: %s/%s' % (finished, N))