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# Example dns_mass_resolve.py

     1#!/usr/bin/python
     2# gevent-test-requires-resource: network
     3"""Resolve hostnames concurrently, exit after 2 seconds.
     4
     5Under the hood, this might use an asynchronous resolver based on
     6c-ares (the default) or thread-pool-based resolver.
     7
     8You can choose between resolvers using GEVENT_RESOLVER environment
     9variable. To enable threading resolver:
    10
    11    GEVENT_RESOLVER=thread python dns_mass_resolve.py
    12"""
    13from __future__ import print_function
    14import gevent
    15from gevent import socket
    16from gevent.pool import Pool
    17
    18N = 1000
    19# limit ourselves to max 10 simultaneous outstanding requests
    20pool = Pool(10)
    21finished = 0
    22
    23
    24def job(url):
    25    global finished
    26    try:
    27        try:
    28            ip = socket.gethostbyname(url)
    29            print('%s = %s' % (url, ip))
    30        except socket.gaierror as ex:
    31            print('%s failed with %s' % (url, ex))
    32    finally:
    33        finished += 1
    34
    35with gevent.Timeout(2, False):
    36    for x in range(10, 10 + N):
    37        pool.spawn(job, '%s.com' % x)
    38    pool.join()
    39
    40print('finished within 2 seconds: %s/%s' % (finished, N))

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