pulsar 0.1.0

Concurrent server and message queues

Event driven network library for python. Tested in Windows and Linux, it requires python 2.6 and up, including python 3.

An example of a web server written with pulsar which responds with “Hello World!” for every request:

import pulsar

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


if __name__ == '__main__':
    wsgi = pulsar.require('wsgi')
    return wsgi.createServer(callable = hello, **kwargs).run()

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 or multi-threading mode.

Applications

Pulsar design allows for a host of different applications to be implemented in an elegant and efficient way. It includes the following

• Http server.

• RPC server.

• Distributed Task Queue.

• Pulsar shell for asynchronous scripting (posix only).

• Asynchronous testing suite.

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 library multiprocessing.Queue class. Two special classes of actors are the Arbiter, used as a singletone, and the Monitor, a manager of several actors performing similar functions.

More information about design and philosophy in the documentations.

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 event-loop implementation), celery (the task queue application) and many other open-source efforts.