023a061587
By default, Python 2.*'s standard library "socket" module performs 8K writes. For 10ge networks, with large MTUs (typically 9,000), this is not optimal. We tie the default buffer size to the client_chunk_size paramter for the proxy server, and to the network_chunk_size for the object server. One might be tempted to ask, isn't there a way to set this value on a per-request basis? This author was unable to find a reference to the _fileobject in the context of WSGI. By the time a request pass to a WSGI object's __call__ method, the "wfile" attribute of the req.environ['eventlet.input'] (Input) object has been set to None, and the "rfile" attribute is the object wrapping the socket for reading, not writing. One might also be tempted to ask, why not just override the wsgi.HttpProtocol's "wbufsize" class attribute instead? Until eventlet/wsgi.py is fixed, we can't set wsgi.HttpProtocol.wbufsize to anything but zero (the default, see Python's SocketServer.py, StreamRequestHandler class), since Eventlet does not ensure the socket _fileobject's flush() method is called after Eventlet invokes a write() method on the same. NOTE: wbufsize (a class attribute of StreamRequestHandler originally, not to be confused with the standard library's socket._fileobject._wbufsize class attribute) is used for the bufsize parameter of the connection object's makefile() method. As a result, the socket's _fileobject code uses that value to set both _rbufsize and _wbufsize. While that would allow us to transmit in 64KB chunks, it also means that write() and writeline() method calls on the socket _fileobject are only transmitted once 64KB have been accumulated, or a flush() is called. As for performance improvement: Run 8KB 64KB 0 8.101 6.367 1 7.892 6.216 2 7.732 6.246 3 7.594 6.229 4 7.594 6.292 5 7.555 6.230 6 7.575 6.270 7 7.528 6.278 8 7.547 6.304 9 7.550 6.313 Average 7.667 6.275 1.3923 18.16% Run using the following after adjusting the test value for obj_len to 1 GB: nosetests -v --nocapture --nologcapture \ test/unit/proxy/test_server.py:TestProxyObjectPerformance.test_GET_debug_large_file Change-Id: I4dd93acc3376e9960fbdcdcae00c6d002e545894 Signed-off-by: Peter Portante <peter.portante@redhat.com>
Swift
A distributed object storage system designed to scale from a single machine to thousands of servers. Swift is optimized for multi-tenancy and high concurrency. Swift is ideal for backups, web and mobile content, and any other unstructured data that can grow without bound.
Swift provides a simple, REST-based API fully documented at http://docs.openstack.org/.
Swift was originally developed as the basis for Rackspace's Cloud Files and was open-sourced in 2010 as part of the OpenStack project. It has since grown to include contributions from many companies and has spawned a thriving ecosystem of 3rd party tools. Swift's contributors are listed in the AUTHORS file.
Docs
To build documentation install sphinx (pip install sphinx), run
python setup.py build_sphinx, and then browse to /doc/build/html/index.html.
These docs are auto-generated after every commit and available online at
http://docs.openstack.org/developer/swift/.
For Developers
The best place to get started is the "SAIO - Swift All In One". This document will walk you through setting up a development cluster of Swift in a VM. The SAIO environment is ideal for running small-scale tests against swift and trying out new features and bug fixes.
You can run unit tests with .unittests and functional tests with
.functests.
Code Organization
- bin/: Executable scripts that are the processes run by the deployer
- doc/: Documentation
- etc/: Sample config files
- swift/: Core code
- account/: account server
- common/: code shared by different modules
- middleware/: "standard", officially-supported middleware
- ring/: code implementing Swift's ring
- container/: container server
- obj/: object server
- proxy/: proxy server
- test/: Unit and functional tests
Data Flow
Swift is a WSGI application and uses eventlet's WSGI server. After the
processes are running, the entry point for new requests is the Application
class in swift/proxy/server.py. From there, a controller is chosen, and the
request is processed. The proxy may choose to forward the request to a back-
end server. For example, the entry point for requests to the object server is
the ObjectController class in swift/obj/server.py.
For Deployers
Deployer docs are also available at http://docs.openstack.org/developer/swift/. A good starting point is at http://docs.openstack.org/developer/swift/deployment_guide.html
You can run functional tests against a swift cluster with .functests. These
functional tests require /etc/swift/test.conf to run. A sample config file
can be found in this source tree in test/sample.conf.
For Client Apps
For client applications, official Python language bindings are provided at http://github.com/openstack/python-swiftclient.
Complete API documentation at http://docs.openstack.org/api/openstack-object-storage/1.0/content/
For more information come hang out in #openstack-swift on freenode.
Thanks,
The Swift Development Team