a91e740b7f
* Restructure "Using third-party Python packages" page to focus on the "Mach commands"/"adding a Python package" use case since that's why most people will be looking at these docs. * Document the `<site>_virtualenv_packages.txt` behaviour and how it relates to a Mach command's definition. * Simplify the information around using a non-PyPI index to reference the RelEng docs directly. It's a shame that the existing docs don't explain how to identify tasks that need to use the internal mirror, because I'm not sure either. There's existing cases of ad-hoc `pip` installs //not// using the mirror, but the pattern isn't clear to me. * Remove the "specify hashes" information, since the centralized solution (will) automatically manage this internally. * Arguably, it's still beneficial instructions for ad-hoc `pip install` usages, but those are frowned upon today anyways - use the centralized solution! Differential Revision: https://phabricator.services.mozilla.com/D138931
127 lines
4.7 KiB
ReStructuredText
127 lines
4.7 KiB
ReStructuredText
.. _mach_faq:
|
|
|
|
==========================
|
|
Frequently Asked Questions
|
|
==========================
|
|
|
|
How do I report bugs?
|
|
---------------------
|
|
|
|
Bugs against the ``mach`` core can be filed in Bugzilla in the `Firefox
|
|
Build System::Mach
|
|
Core <https://bugzilla.mozilla.org/enter_bug.cgi?product=Firefox%20Build%20System&component=Mach%20Core>`__ component.
|
|
|
|
.. note::
|
|
|
|
Most ``mach`` bugs are bugs in individual commands, not bugs in the core
|
|
``mach`` code. Bugs for individual commands should be filed against the
|
|
component that command is related to. For example, bugs in the
|
|
*build* command should be filed against *Firefox Build System ::
|
|
General*. Bugs against testing commands should be filed somewhere in
|
|
the *Testing* product.
|
|
|
|
How do I debug a command failing with a Python exception?
|
|
---------------------------------------------------------
|
|
|
|
You can run a command and break into ``pdb``, the Python debugger,
|
|
when the command is invoked with:
|
|
|
|
.. code-block:: shell
|
|
|
|
./mach --debug-command FAILING-COMMAND ARGS ...
|
|
|
|
How do I profile a slow command?
|
|
--------------------------------
|
|
|
|
To diagnose bottlenecks, you can collect a performance profile:
|
|
|
|
.. code-block:: shell
|
|
|
|
./mach --profile-command SLOW-COMMAND ARGS ...
|
|
|
|
Then, you can visualize ``mach_profile_SLOW-COMMAND.cProfile`` using
|
|
`snakeviz <https://jiffyclub.github.io/snakeviz/>`__:
|
|
|
|
.. code-block:: shell
|
|
|
|
# If you don't have snakeviz installed yet:
|
|
python3 -m pip install snakeviz
|
|
python3 -m snakeviz mach_profile_SLOW-COMMAND.cProfile
|
|
|
|
How do I profile ``mach`` itself?
|
|
---------------------------------
|
|
|
|
Since ``--profile-command`` only profiles commands, you'll need to invoke ``cProfile``
|
|
directly to profile ``mach`` itself:
|
|
|
|
.. code-block:: shell
|
|
|
|
python3 -m cProfile -o mach.cProfile ./mach ...
|
|
python3 -m snakeviz mach.cProfile
|
|
|
|
Is ``mach`` a build system?
|
|
---------------------------
|
|
|
|
No. ``mach`` is just a generic command dispatching tool that happens to have
|
|
a few commands that interact with the real build system. Historically,
|
|
``mach`` *was* born to become a better interface to the build system.
|
|
However, its potential beyond just build system interaction was quickly
|
|
realized and ``mach`` grew to fit those needs.
|
|
|
|
How do I add features to ``mach``?
|
|
----------------------------------
|
|
If you would like to add a new feature to ``mach`` that cannot be implemented as
|
|
a ``mach`` command, the first step is to file a bug in the
|
|
``Firefox Build System :: Mach Core`` component.
|
|
|
|
Should I implement X as a ``mach`` command?
|
|
-------------------------------------------
|
|
|
|
There are no hard or fast rules. Generally speaking, if you have some
|
|
piece of functionality or action that is useful to multiple people
|
|
(especially if it results in productivity wins), then you should
|
|
consider implementing a ``mach`` command for it.
|
|
|
|
Some other cases where you should consider implementing something as a
|
|
mach command:
|
|
|
|
- When your tool is a random script in the tree. Random scripts are
|
|
hard to find and may not conform to coding conventions or best
|
|
practices. Mach provides a framework in which your tool can live that
|
|
will put it in a better position to succeed than if it were on its
|
|
own.
|
|
- When the alternative is a ``make`` target. The build team generally does
|
|
not like one-off ``make`` targets that aren't part of building (read:
|
|
compiling) the tree. This includes things related to testing and
|
|
packaging. These weigh down ``Makefiles`` and add to the burden of
|
|
maintaining the build system. Instead, you are encouraged to
|
|
implement ancillary functionality in Python. If you do implement something
|
|
in Python, hooking it up to ``mach`` is often trivial.
|
|
|
|
How do I use 3rd-party Python packages in my ``mach`` command?
|
|
--------------------------------------------------------------
|
|
|
|
See :ref:`Using third-party Python packages`.
|
|
|
|
How does ``mach`` fit into the modules system?
|
|
----------------------------------------------
|
|
|
|
Mozilla operates with a `modules governance
|
|
system <https://www.mozilla.org/about/governance/policies/module-ownership/>`__ where
|
|
there are different components with different owners. There is not
|
|
currently a ``mach`` module. There may or may never be one; currently ``mach``
|
|
is owned by the build team.
|
|
|
|
Even if a ``mach`` module were established, ``mach`` command modules would
|
|
likely never belong to it. Instead, ``mach`` command modules are owne by the
|
|
team/module that owns the system they interact with. In other words, ``mach``
|
|
is not a power play to consolidate authority for tooling. Instead, it aims to
|
|
expose that tooling through a common, shared interface.
|
|
|
|
|
|
Who do I contact for help or to report issues?
|
|
----------------------------------------------
|
|
|
|
You can ask questions in
|
|
`#build <https://chat.mozilla.org/#/room/#build:mozilla.org>`__.
|