celery/examples/eventlet/README.rst

==================================
  Example using the Eventlet Pool
==================================

Introduction
============

This is a Celery application containing two example tasks.

First you need to install Eventlet, and also recommended is the `dnspython`
module (when this is installed all name lookups will be asynchronous)::

    $ pip install eventlet
    $ pip install dnspython
    $ pip install requests

Before you run any of the example tasks you need to start
the worker::

    $ cd examples/eventlet
    $ celery worker -l info --concurrency=500 --pool=eventlet

As usual you need to have RabbitMQ running, see the Celery getting started
guide if you haven't installed it yet.

Tasks
=====

* `tasks.urlopen`

This task simply makes a request opening the URL and returns the size
of the response body::

    $ cd examples/eventlet
    $ python
    >>> from tasks import urlopen
    >>> urlopen.delay('http://www.google.com/').get()
    9980

To open several URLs at once you can do::

    $ cd examples/eventlet
    $ python
    >>> from tasks import urlopen
    >>> from celery import group
    >>> result = group(urlopen.s(url)
    ...                     for url in LIST_OF_URLS).apply_async()
    >>> for incoming_result in result.iter_native():
    ...     print(incoming_result)

* `webcrawler.crawl`

This is a simple recursive web crawler.  It will only crawl
URLs for the current host name.  Please see comments in the
`webcrawler.py` file.