Eventlet

Eventlet is a concurrent networking library for Python that allows you to change how you run your code, not how you write it.

  • It uses epoll or libevent for highly scalable non-blocking I/O.
  • Coroutines ensure that the developer uses a blocking style of programming that is similar to threading, but provide the benefits of non-blocking I/O.
  • The event dispatch is implicit, which means you can easily use Eventlet from the Python interpreter, or as a small part of a larger application.

It's easy to get started using Eventlet, and easy to convert existing applications to use it. Start off by looking at examples, common design patterns, and the list of the basic API primitives.

API Documentation

Installation

To install eventlet, simply: 

easy_install eventlet

Alternately, you can download the source tarball from PyPi:

Discussion

eventletdev at lists.secondlife.com

This is a relatively low-traffic list about using and developing eventlet. Look through the archives for some useful information and possible answers to questions.

There's an IRC channel dedicated to eventlet: #eventlet on freenode. It's a pretty chill place to hang out!

Development

trunk repository

We use Mercurial for our source control, hosted by BitBucket. It's easy to branch off the main repository and contribute patches, tests, and documentation back upstream.

Bugs

Bug Report Form

No registration is required. Please be sure to report bugs as effectively as possible, to ensure that we understand and act on them quickly.

Web Crawler ExampleΒΆ

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",
     "https://wiki.secondlife.com/w/images/secondlife.jpg",
     "http://us.i1.yimg.com/us.yimg.com/i/ww/beta/y3.gif"]

import eventlet
from eventlet.green import urllib2

def fetch(url):

  return urllib2.urlopen(url).read()

pool = eventlet.GreenPool()

for body in pool.imap(fetch, urls):
  print "got body", len(body)

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