`-Zthreads` is slower the more cores I add
Open
Nobody has claimed this yet.
S-needs-repro
WG-compiler-performance
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
In my crates I haven't actually gotten a speedup from more threads. In fact, quite the opposite!
The more threads I add the slower it becomes, 1 being the fastest.
rustc --version
rustc 1.82.0-nightly (91376f416 2024-08-12)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Begin by reproducing the report with rustc 1.82.0-nightly (91376f416 2024-08-12), varying -Zthreads on a minimal crate and measuring compilation time. The issue names no crate, command, source file, or test, so first establish a concrete reproduction and trace the compiler phase responsible before determining what a fix or regression test should cover.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers, performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100