To what extent is the performance impact of caching / not caching

.cache/pants/named_caches

? I noticed that this directory is extremely large (on the order of gigabytes), and caching it is somewhat expensive because it takes a long time to download (and upload) this cache

Thats the "cheat" cache, where we point tools to if they are multi-process safe. Namely what you're likely seeing is a large

pex_root

, which among other things, is where all your downloaded dependencies are stored 🙂

I see… so the reason for this cache being really big is due to the size of my dependencies?

Don't take my word for it,

du

the subdirs 😛

Ahh, turned out to be an issue with me constantly uploading to the cache and not nuking when it got too big…

@witty-crayon-22786 any pointers for trimming the PEX root? Seems like it'll just grow and grow and grow?

https://www.pantsbuild.org/docs/using-pants-in-ci discusses this and recommends a particular script

Yeah, the nuke script 🙂 I didn’t have that previously but will probably add it in

but https://github.com/pantsbuild/pants/issues/14364 discusses how the advice there could be more precise: the entire

pex_root

is not useful to cache, per-se

Also check out this blog about how remote caching makes this much much better https://blog.pantsbuild.org/better-ci-cd-caching-with-pants/