python-gevent/examples/dns_mass_resolve.py

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Python
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#!/usr/bin/python
# gevent-test-requires-resource: network
"""Resolve hostnames concurrently, exit after 2 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
"""
from __future__ import print_function
import gevent
from gevent import socket
from gevent.pool import Pool
N = 1000
# limit ourselves to max 10 simultaneous outstanding requests
pool = Pool(10)
finished = 0
def job(url):
global finished
try:
try:
ip = socket.gethostbyname(url)
print('%s = %s' % (url, ip))
except socket.gaierror as ex:
print('%s failed with %s' % (url, ex))
finally:
finished += 1
with gevent.Timeout(2, False):
for x in range(10, 10 + N):
pool.spawn(job, '%s.com' % x)
pool.join()
print('finished within 2 seconds: %s/%s' % (finished, N))