rust-lang / rust-lang/rustup

improve `proxy_mode` (e.g. rustc wrapper) startup time?

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#2,626 54 comments 8 reactions 0 assignees View on GitHub

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enhancement help wanted performance
Dominant language
Rust
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Merged PRs (30d)
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Description

time ~/.rustup/toolchains/master/bin/rustc >& /dev/null
0,040 total

time ~/.cargo/bin/rustc >& /dev/null
0,272 total

That's almost 7x slower.
I wonder if there is some something we can do to get these numbers a bit closer?

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Research direction

Reproduce the comparison between ~/.rustup/toolchains/master/bin/rustc and ~/.cargo/bin/rustc using the provided time commands, then trace rustup's proxy_mode startup path. Measure the wrapper overhead and identify where the extra startup time is introduced. Done means bringing the proxy-mode timing materially closer to the direct rustc timing without changing its behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
performance, tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
45/100

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