Our workflows and Dockerfiles now use Ninja on Linux & Mac, which
enables safe parallel builds. This significantly speeds up our
workflows.
GitHub Actions typical compilation times (build step only):
- Linux 19m => 9m
- macOS 23m => 8m
- Windows 12m => 10m
- Linux arm64 (self-hosted) 72m => 29m
- Docker build 25m => 14m
Overall workflow time: 84m => 33m
Compilation time on my workstation (12 CPUs @3.3GHz): 15m => 3m
This also adds a new environment variable "PACKAGER_LOW_MEMORY_BUILD".
If defined when CMake is first run, this will configure the build to
disable parallel linking to reduce memory usage. This helps us avoid
failures on our self-hosted arm64 machines, where 6 CPUs share 4GB of
RAM.
NOTE: Parallel builds are **NOT** recommended with Unix Makefiles due to
the use of excessive RAM during parallel linking. Unix Makefiles, unlike
Ninja, cannot be configured to restrict parallel linking during a
parallel build. Anecdotally, parallel builds with Makefiles have
exhausted a system with 32GB RAM. (My workstation.)
In a follow-up, I will update the build documentation to refer to CMake
and recommend all of the flags now used in our workflows.
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