Profiling
=========

Using profilers
---------------

Bazaar has some built-in support for collecting and saving profiling
information. In the simpliest case, the ``--lsprof`` option can be used as
shown below::

  bzr --lsprof ...

This will dump the profiling information to stdout before exiting.
Alternatively, the ``--lsprof-file`` option can be used to specify a filename
to save the profiling data into to. By default, profiling data saved to a
file is a pickled Python object making it possible to reload the data and
do with it what you will. For convenience though:

* if the filename ends in ``.txt``, it will be dumped in a text format.

* if the filename either starts with ``callgrind.out`` or ends with
  ``.callgrind``, it will be converted to a format loadable by the
  KCacheGrind visualization tool.

Note that KCacheGrind's Open Dialog has a default filter than only shows
files starting with ``callgrind.out`` so the longer filename is usually
preferable. Here is an example of how to use the ``--lsprof-file`` option
in combination with KCacheGrind to visualize what the ``status`` command
is doing::

  bzr --lsprof-file callgrind.out.st001 status
  kcachegrind callgrind.out.st001 &

.. Note:: bzr also has a ``--profile`` option that uses the hotshot profiler
   instead of the lsprof profiler. The hotshot profiler can be useful
   though the lsprof one is generally recommended. See
   http://docs.python.org/lib/node795.html.

Note that to use ``--lsprof`` you must install the lsprof module, which you
can get with::

  svn co http://codespeak.net/svn/user/arigo/hack/misc/lsprof


Profiling locks
---------------

Bazaar can log when locks are taken or released, which can help in
identifying unnecessary lock traffic.  This is activated by the ``-Dlock``
global option.

This writes messages into ``~/.bzr.log``.
At present this only logs actions relating to the on-disk lockdir.  It 
doesn't describe actions on in-memory lock counters, or OS locks (which
are used for dirstate.)


Profiling HPSS Requests
-----------------------

When trying to improve network performance, it is often useful to know
what requests are being made, and how long they are taking. The ``-Dhpss``
global option will enable logging smart server requests, including the
time spent in each request.
