Given it is known how slow Python at starting up, I am puzzled why Mozilla continue to use it in build scripts. Perl is just as portable but starts up like 10 times faster.
Indeed. As hg is moving to use more and more Rust:
https://www.mercurial-scm.org/wiki/OxidationPlan?action=info
Basically I have some hope that eventaully rust will take over, however writing the core components is a critical first step and selling it for the immediate benifits is much easier then selling a complete rewrite.
No love for Haskell[0]? It does look like the best system scripting language out there right now... I have just never tried it to be sure :(
0: http://www.haskellforall.com/2015/01/use-haskell-for-shell-s...
> Changing gears, my day job is maintaining Firefox's build system. We use Python heavily in the build system. And again, Python startup overhead is problematic. I don't have numbers offhand, but we invoke likely a few hundred Python processes as part of building Firefox. It should be several thousand. But, we've had to "hack" parts of the build system to "batch" certain build actions in single process invocations in order to avoid Python startup overhead. This undermines the ability of some build tools to formulate a reasonable understanding of the DAG and it causes a bit of pain for build system developers and makes it difficult to achieve "no-op" and fast incremental builds because we're always invoking certain Python processes because we've had to move DAG awareness out of the build backend and into Python. At some point, we'll likely replace Python code with Rust so the build system is more "pure" and easier to maintain and reason about.
The link we're discussing is about Python runs for the Mercurial test suite. The Firefox build is mentioned in passing. It's not what the post is discussing (and doesn't get into numbers there).
For tests, yes.
I can't fathom what Mozilla does for thousands of Python invocations during build. Maybe it's test runs as well?