/brz/remove-bazaar

Contributing to the performance drive

=====================================

.. contents:: :local:

What needs doing?

-----------------

There is plenty of code to write. Testers are always welcome for experimental

changes. In general, pick a BLUE node from performance.png which has nothing

pointing at it that is also BLUE, and start working on that.

Adhoc performance work can also be done. One useful tool is the 'evil' debug

flag. For instance running ``bzr -Devil commit -m "test"`` will log a backtrace

to the bzr log file for every method call which triggers a slow or non-scalable

part of the bzr library. So checking that a given command with ``-Devil`` has

no backtraces logged to the log file is a good way to find problem function

calls that might be nested deep in the code base.

Status

------

The performance drive is well under way. At the moment we are finalising the

analysis documents from the sprint at London. If you were not at that sprint,

please read the analysis documents - consider them living documents much like

code, to be patched and corrected.

If you were at the London performance sprint, please help finish documenting

the core command analysis work. The core commands that have not been analysed

are listed in performance.dot as the BLUE nodes. For quick reference:

* status

* log

* diff

* uncommit

* missing

* update

* cbranch

Once a given command has had its analysis created, the bottleneck of 'folk who

attended London' is removed. The next task is in general the creation of a

targeted API stack for that command. This API stack is done by starting with

the cmd object in ``builtins.py`` and cleaning up the code so that the API used

there is one which allows an implementation matching the analysis document.

This then gets repeated, iteratively, on each of the called API's, until all

the current slow code is cleanly abstracted behind the ``Tree``, ``Branch`` and

``Repository`` API's.

Resources

---------

The usual resources for contributing to bzr - the mailing list, wiki, bug

tracker and IRC channels are documented in the HACKING_ document. Additionally

there are members of the project focusing on performance at the moment who are

willing to mentor contributors on performance issues. Just send a mail to the

list asking for mentoring on the step of the performance plan you want to help

with.

.. _HACKING: HACKING.htm