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pulsar 0.7.3

Package Documentation

Latest Version: 0.8.1

Event driven concurrent framework for python. With pulsar you can write asynchronous servers performing one or several activities in different threads and/or processes.

PyPI:Latest PyPI version Number of PyPI downloads
Master CI:master-build coverage-master
Dev CI:dev-build coverage-dev
Documentation:http://pythonhosted.org/pulsar/
Downloads:http://pypi.python.org/pypi/pulsar
Source:https://github.com/quantmind/pulsar
Mailing list:google user group
Platforms:Linux, OS X, Windows. Python 2.6, 2.7, 3.2, 3.3, pypy
Keywords:server, asynchronous, concurrency, actor, thread, process, socket, task queue, wsgi, websocket, redis, json-rpc

An example of a web server written with pulsar application framework which responds with "Hello World!" for every request:

from pulsar.apps import wsgi

def hello(environ, start_response):
    '''Pulsar HTTP "Hello World!" application'''
    data = b'Hello World!\n'
    status = '200 OK'
    response_headers = [
        ('Content-type','text/plain'),
        ('Content-Length', str(len(data)))
    ]
    start_response(status, response_headers)
    return [data]


if __name__ == '__main__':
    wsgi.WSGIServer(callable=hello).start()

Pulsar's goal is to provide an easy way to build scalable network programs. In the "Hello world!" web server example above, many client connections can be handled concurrently. Pulsar tells the operating system (through epoll or select) that it should be notified when a new connection is made, and then it goes to sleep.

Pulsar uses the multiprocessing module from the standard python library and it can be configured to run in multi-processing mode, multi-threading mode or a combination of the two.

Installing

Pulsar is a stand alone python library and it can be installed via pip:

pip install pulsar

easy_install or downloading the tarball from pypi.

If cython is available, c extensions will be compiled and installed.

Applications

Pulsar design allows for a host of different applications to be implemented in an elegant and efficient way. Out of the box it is shipped with the the following:

  • Socket servers.
  • WSGI server.
  • JSON-RPC WSGI middleware.
  • Web Sockets WSGI middleware.
  • Publish/Subscribe middleware.
  • Distributed task queue.
  • Shell for asynchronous scripting.
  • Asynchronous test suite.
  • Application to run a django site with pulsar.
  • twisted integration (python 2 only).

Examples

Check out the examples directory for various working applications created using pulsar alone. It includes:

  • Hello world! wsgi example.
  • An Httpbin wsgi application (similar to http://httpbin.org/).
  • An HTTP Proxy server with headers middleware.
  • A simple JSON-RPC Calculator server.
  • A taskqueue application with a JSON-RPC interface.
  • Websocket graph.
  • Websocket Web Chat.
  • django web site with a websocket middleware to handle a web chat.
  • A web mail application which uses twisted IMAP4 API.
  • The dining philosophers problem.
  • Asynchronous shell.

Design

Pulsar internals are based on actors primitive. Actors are the atoms of pulsar's concurrent computation, they do not share state between them, communication is achieved via asynchronous inter-process message passing, implemented using the standard python socket library.

Two special classes of actors are the Arbiter, used as a singleton, and the Monitor, a manager of several actors performing similar functions. The Arbiter runs the main eventloop and it controls the life of all actors. Monitors manage group of actors performing similar functions, You can think of them as a pool of actors.

More information about design and philosophy in the documentation.

Add-ons

Pulsar checks if some additional libraries are available at runtime, and uses them to add additional functionalities or improve performance:

  • http-parser: upgrade the HTTP parser to a faster C version.
  • setproctitle: if installed, pulsar can use it to change the processes names of the running application.
  • psutil: if installed, a system key is available in the dictionary returned by Actor info method.
  • ujson: if installed it is used instead of the native json module.
  • twisted: required by the pulsar.apps.tx application when using pulsar with twisted protocols.
  • django: required by the pulsar.apps.pulse application.

Running Tests

Pulsar test suite uses the pulsar test application. If you are using python 2.6 you need to install unittest2, and if not running on python 3.3, the mock library is also needed. To run tests:

python runtests.py

For options and help type:

python runtests.py -h

pep8 check (requires pep8 package):

python runtests.py --pep8

Kudos

Pulsar project started as a fork of gunicorn (from where the arbiter idea) and has been developed using ideas from nodejs (api design), twisted (the deferred implementation), tornado web server (the initial event-loop implementation), celery (the task queue application) and, since version 0.5, tulip and PEP-3156. In addition, pulsar uses several snippet of code from around the open-source community, in particular:

  • A python HTTP Parser originally written by benoitc.
  • A url Rule class originally from werkzeug.

Contributing

Development of pulsar happens at Github. We very much welcome your contribution of course. To do so, simply follow these guidelines:

License

This software is licensed under the New BSD License. See the LICENSE file in the top distribution directory for the full license text.

 
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pulsar-0.7.3.tar.gz (md5) Source 2013-12-12 399KB
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