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mozilla / sccache

Sccache is a ccache-like tool. It is used as a compiler wrapper and avoids compilation when possible. Sccache has the capability to utilize caching in remote storage environments, including various cloud storage options, or alternatively, in local storage.
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Fix rustc -Z ls handling #2290

Open lissyx opened 6 days ago

lissyx commented 6 days ago

I was investigating a high memory usage on sccache rust compilation part and I came accross a failure in the build log https://github.com/mozilla/sccache/blob/b0a6355d9ef18df3d9d26531254d8ab52ba306ca/src/compiler/rust.rs#L2388.

At first I assumed it was just a byproduct of configure step, but it looks like -Z ls changes in https://github.com/rust-lang/rust/commit/ff00763dd1c542abe9897ff62c3acff5baa6d2eb#diff-03c3ed2f6e27e58df63382e00323eea6fd1ce3a4f9546941b2b717fead25e520

One might need to update to -Z ls=root.

lissyx commented 6 days ago

Running the changes locally, I think it also fixes the high memory usage that prompted that investigation: I had to kill sometime (or OOM killker did) because sccache was consuming > 65% of RAM (out of 32GB ...). I have not been able to see more than 16% after this changed (mach build -j128 on a 16 cores laptop + 32GB RAM with sccache-dist setup and a desktop with 128 cores and 128GB of RAM).