Eventlet

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.

• Example code: Eventlet/Examples
• Subversion repository: http://svn.secondlife.com/svn/eventlet
• Trac page: http://svn.secondlife.com/trac/eventlet
• Mailing list: https://lists.secondlife.com/cgi-bin/mailman/listinfo/eventletdev

Documentation

Eventlet/Documentation

Releases

Name	Date	Zip	SVN
beta-1	Aug 24, 2007	[1]	[2]

Requirements

Eventlet runs on Python version 2.3 or greater, with the following dependencies:

• greenlet
• pyOpenSSL if you want to use ssl sockets
• (if running python versions < 2.4) a deque object in a collections module. One option is to copy this deque into a file called collections.py.

Eventlet at Linden

eventlet is the networking library used to implement the backbone architecture. Backbone is primarily an http server, and as such uses the eventlet.httpd module. eventlet itself is responsible only for handling http protocol-level semantics; "web framework" concepts such as URL traversal and html rendering are implemented in a separate python package, mulib.

Limitations

• Not enough test coverage -- the goal is 100%, but we are not there yet.
• The SSL client does not properly connect to the SSL server, though both client and server interoperate with other SSL implementations (e.g. curl and apache).
  • We could use a) a unit test that reproduces the bug (rather than the hand-testing we have been doing) and b) a fix for said bug.
• 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.

Eventlet History

Eventlet began life as Donovan Preston was talking to Bob Ippolito about coroutine-based non-blocking networking frameworks in Python. Most non-blocking frameworks require you to run the "main loop" in order to perform all network operations, but Donovan wondered if a library written using a trampolining style could get away with transparently running the main loop any time i/o was required, stopping the main loop once no more i/o was scheduled. Bob spent a few days during PyCon 2006 writing a proof-of-concept. He named it eventlet, after the coroutine implementation it used, greenlet. Donovan began using eventlet as a light-weight network library for his spare-time project Pavel, and also began writing some unittests.

• http://svn.red-bean.com/bob/eventlet/trunk/

When Donovan started at Linden Lab in May of 2006, he added eventlet as an svn external in the indra/lib/python directory, to be a dependency of the yet-to-be-named backbone project (at the time, it was named restserv). However, including eventlet as an svn external meant that any time the externally hosted project had hosting issues, Linden developers were not able to perform svn updates. Thus, the eventlet source was imported into the linden source tree at the same location, and became a fork.

Bob Ippolito has ceased working on eventlet and has stated his desire for Linden to take it's fork forward to the open source world as "the" eventlet.