f1e4d33d02
Under certain conditions, if the WSGI iterable yields an empty string,
it can cause the response to be terminated.
The conditions are as follows:
* no minimum chunk size (eventlet.wsgi.server() was called with
minimum_chunk_size=0, or
env['eventlet.minimum_write_chunk_size'] = 0)
* chunked transfer-encoding on the response
In this case, if the WSGI iterable yields an empty string, then
eventlet.wsgi obligingly turns that into "0\r\n\r\n" and writes that
to the socket. This, of course, terminates the response as far as the
client is concerned. However, eventlet.wsgi doesn't notice, so it'll
happily keep calling next(app_iter) and sending the chunks.
If Connection: keep-alive is set, the client might then send the next
request, read some chunked response body, fail to parse it, and then
disconnect.
In other cases, either the 0-byte chunk is saved in the chunk buffer
until the minimum chunk size is met, or 0 bytes get written to the
socket. Those are both no-ops.
This commit discards 0-byte chunks from the WSGI iterable.
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 the examples, common design patterns, and the list of basic API primitives.
Quick Example
Here's something you can try right on the command line:
% python
>>> import eventlet
>>> from eventlet.green import urllib2
>>> gt = eventlet.spawn(urllib2.urlopen, 'http://eventlet.net')
>>> gt2 = eventlet.spawn(urllib2.urlopen, 'http://secondlife.com')
>>> gt2.wait()
>>> gt.wait()Getting Eventlet
The easiest way to get Eventlet is to use pip:
pip install eventletThe development tip is available as well:
pip install 'eventlet==dev'Building the Docs Locally
To build a complete set of HTML documentation, you must have Sphinx, which can be found at http://sphinx.pocoo.org/ (or installed with pip install Sphinx):
cd doc
make htmlThe built html files can be found in doc/_build/html afterward.
Twisted
Eventlet had Twisted hub in the past, but community interest to this integration has dropped over time, now it is not supported, so with apologies for any inconvenience we discontinue Twisted integration.
If you have a project that uses Eventlet with Twisted, your options are:
- use last working release eventlet==0.14
- start a new project with only Twisted hub code, identify and fix problems. As of eventlet 0.13, EVENTLET_HUB environment variable can point to external modules.
- fork Eventlet, revert Twisted removal, identify and fix problems. This work may be merged back into main project.
Apologies for any inconvenience.