meinheld 0.5.5

What’s this

This is a high performance python wsgi web server.

Thus this is yet an another asynchronous web server like gevent.

And meinheld is a WSGI compliant web server. (PEP333 and PEP3333 supported)

You can also join us in meinheld mailing list and #meinheld on freenode

Requirements

meinheld requires Python 2.x >= 2.6 or Python 3.x >= 3.2 . and greenlet == 0.4.0.

meinheld supports Linux, FreeBSD, Mac OS X.

Installation

Install from pypi:

$ easy_install -ZU meinheld

Install from source:

$ python setup.py install

meinheld supports gunicorn.

To install gunicorn (only python 2.x):

$ easy_install -ZU gunicorn

Basic Usage

simple wsgi app:

from meinheld import server

def hello_world(environ, start_response):
    status = '200 OK'
    res = "Hello world!"
    response_headers = [('Content-type','text/plain'),('Content-Length',str(len(res)))]
    start_response(status, response_headers)
    return [res]

server.listen(("0.0.0.0", 8000))
server.run(hello_world)

with gunicorn. user worker class “egg:meinheld#gunicorn_worker” or “meinheld.gmeinheld.MeinheldWorker”:

$ gunicorn --workers=2 --worker-class="egg:meinheld#gunicorn_worker" gunicorn_test:app

Continuation

meinheld provides a simple continuation API (based on greenlet).

To enable continuations, use ContinuationMiddleware. get Continuation from wsgi environ.

Continuation objects have two very interesting methods, suspend and resume.

For example:

from meinheld import server
from meinheld import middleware

def app(environ, start_response):
    ...

    #get Continuation
    c = environ.get(middleware.CONTINUATION_KEY, None)

    ...

    if condtion:
        waiters.append(c)
        #suspend
        c.suspend()
    else:
        for c in waiters:
            # resume suspend function
            c.resume()

    ...


server.listen(("0.0.0.0", 8000))
server.run(middleware.ContinuationMiddleware(hello_world))

For more info see http://github.com/mopemope/meinheld/tree/master/example/chat/

Websocket

meinheld support Websockets. use WebSocketMiddleware.

For example:

from flask import Flask, render_template, request
from meinheld import server, middleware

SECRET_KEY = 'development key'
DEBUG=True

app = Flask(__name__)
app.config.from_object(__name__)


participants = set()


@app.route('/')
def index():
    return render_template('websocket_chat.html')

@app.route('/chat')
def chat():
    print request.environ
    ws = request.environ.get('wsgi.websocket')
    participants.add(ws)
    try:
        while True:
            print "ws.wait()..."
            m = ws.wait()
            print "recv msg %s" % m
            if m is None:
                break
            for p in participants:
                print "send message %s" % m
                p.send(m)
    finally:
        participants.remove(ws)
    return ""


if __name__ == "__main__":
    server.listen(("0.0.0.0", 8000))
    server.run(middleware.WebSocketMiddleware(app))

Patching

meinheld provides a few monkeypatches.

from meinheld import patch
patch.patch_all()

Performance

For parsing HTTP requests, meinheld uses Ryan Dahl’s http-parser library.

(see https://github.com/joyent/http-parser)

It is built around the high performance event library picoev.

(see http://developer.cybozu.co.jp/kazuho/2009/08/picoev-a-tiny-e.html)