Eventlet

Eventlet is a networking library written in Python. It achieves high scalability by using non-blocking io while at the same time retaining high programmer usability by using coroutines to make the non-blocking io operations appear blocking at the source code level.

Web Crawler Example

This is a simple web "crawler" that fetches a bunch of urls using a coroutine pool. It has as much concurrency (i.e. pages being fetched simultaneously) as coroutines in the pool.

urls = ["http://www.google.com/intl/en_ALL/images/logo.gif",
       "http://wiki.secondlife.com/w/images/secondlife.jpg",
       "http://us.i1.yimg.com/us.yimg.com/i/ww/beta/y3.gif"]

import time
from eventlet import coros

# this imports a special version of the urllib2 module that uses non-blocking IO
from eventlet.green import urllib2

def fetch(url):
    print "%s fetching %s" % (time.asctime(), url)
    data = urllib2.urlopen(url)
    print "%s fetched %s" % (time.asctime(), data)

pool = coros.CoroutinePool(max_size=4)
waiters = []
for url in urls:
    waiters.append(pool.execute(fetch, url))

# wait for all the coroutines to come back before exiting the process
for waiter in waiters:
    waiter.wait()

basic_usage chat_server_example threading history

modules

Requirements

Eventlet runs on Python version 2.4 or greater, with the following dependencies:

Areas That Need Work

Not enough test coverage -- the goal is 100%, but we are not there yet.
Not tested on Windows

There are probably some simple Unix dependencies we introduced by accident. If you're running Eventlet on Windows and run into errors, let us know.

The eventlet.processes module is known to not work on Windows.

License

Eventlet is made available under the terms of the open source MIT license below.

EVENTLET

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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