[ann] `mach --profile-command ...` can help investigate slow `mach` invocations

[Nick Alexander]

Hi folks,

I just landed Bug 1713173 [1], which adds `mach --profile-command COMMAND`.  If you have an unusually slow `mach` invocation, capture a (Python cProfile) profile and use the suggested tools (snakeviz) to figure out where the time is going.  A line of documentation is available [2].

I wanted to broaden awareness because this has arisen for me a few times [3] and came up independently a few days ago as well [4].

Happy profiling!  Let's make `mach` commands faster!

Nick

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1713173

[2] https://firefox-source-docs.mozilla.org/mach/faq.html

[3] https://bugzilla.mozilla.org/show_bug.cgi?id=1713178

[4] https://bugzilla.mozilla.org/show_bug.cgi?id=1713604