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NSQ for Python

Build Status

Clients

TCP Clients

This library will provide bindings for the TCP interface of nsqd, compatible with three frameworks:

  1. threading / select which should be sufficient for most cases, except for those using a large number of nsqd instances
  2. gevent, which is actually merely a wrapping of the above with monkey-patched threading and select and
  3. tornado for those used to the original official python client.

It also provides the building blocks for exending this client to work with other frameworks as well.

HTTP Clients

This also provides bindings for the HTTP interfaces of nsqlookupd and nsqd for convenience in nsq.http.

Primitives

There are a few primitives you should use when building event-mechanism-specific bindings:

  • connection.Connection simply wraps a socket and knows how to send commands and read as many responses as are available on the wire
  • response has the Response, Error and Message classes which all know how to unpack and pack themselves.
  • util holds some utility methods for packing data and other miscellany

Usage

Both the threading and gevent clients keep the same interface. It's just the internals that differ. In these cases, the Reader might be used like so:

# For the threaded version:
from nsq.reader import Reader
# For the gevent version:
from nsq.gevent import Reader

reader = Reader('topic', 'channel', ...)

for message in reader:
    print message
    message.fin()

If you're using gevent, you might want to have a pool of coroutines running code to consume messages. That would look something like this:

from gevent.pool import Pool
pool = Pool(50)

def consume_message(message):
    print message
    message.fin()

pool.map(consume_message, reader)

Closing

You really ought to close your reader when you're done with it. Fortunately, this is quite-easily done with contextlib:

from contextlib import closing

with closing(Reader('topic', 'channel', ...)) as reader:
    for message in reader:
        ....

Benchmarks

There is a shovel task included in shovel/profile.py that runs a basic consumer benchmark against a local nsqd isntance. The most recent benchmark on a 2011 MacBook Pro shows the select-based Reader consuming about 105k messages / second. With gevent enabled, it does not appear to be statistically significantly different.

Running Tests

You'll need to install a few dependencies before invoking the tests:

pip install -r requirements.txt
make test

This should run the tests and provide coverage information.

Contributing

Help is always appreciated. If you add functionality, please:

  • include a failing test in one commit
  • a fix for the failing test in a subsequent commit
  • don't decrease the code coverage