# gevent

# Example dns_mass_resolve.py

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    #!/usr/bin/python
    """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))

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