Updating lockfiles is slow

[crackcomm]

I wanted to ask if updating lockfiles should be slow (120s~) or maybe I missed some configuration steps?

[illicitonion]

There's a speed/correctness trade-off you can make here.

The slow part of updating lockfiles is cargo downloading the crates.io index.

You can control whether we will try to re-use your existing $CARGO_HOME/homedir index, or download a fresh one for the repository, using the isolated attribute (or env var).

isolated=True (the default) prefers correctness - a bad/corrupt/whatever clone of the crates index may cause problems, but this is incredibly unlikely.

isolated=False prefers speed at the expense that if you have a bad crates index clone, you may see bad results.

Long-term, we expect to benefit from any improvements to cargo here. In particular, when sparse registries stabilise we expect this to get much better, as we will only have to download the crates you care about, not the entire index, which is increasingly huge.

I'm going to close this issue as "answered", but very happy to continue discussion about workarounds or possible improvements!

[crackcomm]

That's very informative @illicitonion, I wish I knew about CARGO_BAZEL_ISOLATED earlier when I was was re-pinning a lot during dev.