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Loading images step currently takes ~30s +- a ton of variance. Linux CI jobs are currently taking 8-20m typically. So image builds can be up to ~6% of wall time. I've been playing around with further increasing Depot runner sizes. That delivers a considerable wall time reduction (<5m builds possible). This increases the percentage overhead of any "CI taxes," like restoring caches and pulling/loading container images. This commit implements a pair of optimizations to enable the image loading step to take as little as 5s: * We parallelize the image decompression + loading using simple `&` + `wait` shell features. * We filter out images that aren't needed for the current job. The filtering isn't fully lean - we don't currently filter out images related to cross-compiling. And we still incur overhead to download images we don't load. Those optimizations will wait for another day.
jjhelmus
approved these changes
Mar 24, 2026
Contributor
|
If you are looking at speeding up CI, splitting building dependencies from cpython and then reusing the built dependencies has the potential for a good improvement. #984 has a start for Windows. |
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Loading images step currently takes ~30s +- a ton of variance.
Linux CI jobs are currently taking 8-20m typically. So image builds can be up to ~6% of wall time.
I've been playing around with further increasing Depot runner sizes. That delivers a considerable wall time reduction (<5m builds possible). This increases the percentage overhead of any "CI taxes," like restoring caches and pulling/loading container images.
This commit implements a pair of optimizations to enable the image loading step to take as little as 5s:
&+waitshell features.The filtering isn't fully lean - we don't currently filter out images related to cross-compiling.
And we still incur overhead to download images we don't load.
Those optimizations will wait for another day.