rust-analyzer: lightweight profile (disable cachePriming + cargo.auto…#1557
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davidcforbes wants to merge 1 commit into
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rust-analyzer: lightweight profile (disable cachePriming + cargo.auto…#1557davidcforbes wants to merge 1 commit into
davidcforbes wants to merge 1 commit into
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…reload) serena's symbol tools (find_symbol, find_referencing_symbols, …) only need the symbol index, but the LSP is launched with VS Code's full heavyweight defaults. On a large, actively-built Rust workspace these drove rust-analyzer to 40+ GB RSS and triggered a full re-index on every external `cargo build` (target/ churn). Disabling the two eager/auto re-indexing drivers keeps symbol navigation working at a fraction of the memory: - cachePriming.enable: True -> False (no eager whole-workspace+deps index) - cargo.autoreload: True -> False (no re-index storm on target/ changes) checkOnSave is intentionally LEFT enabled: serena's get_diagnostics_for_file relies on flycheck (`cargo check`) for Rust diagnostics, and disabling it makes that tool return empty (test/solidlsp/rust/test_rust_diagnostics.py fails with []). checkOnSave only spawns transient `cargo check` child processes and is not a driver of rust-analyzer's resident RSS, so keeping it on preserves diagnostics at no meaningful memory cost. Observed on a rustback (multi-crate + rustic_core fork) workspace: repeated 40-44 GB rust-analyzer processes under serena with no VS Code present. Suggest upstream expose a "lightweight"/symbol-only RA profile or a config toggle. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Thanks, that makes sense and helps us - we noticed the slow startup on large rust projects. On ubuntu a rust diagnostics test fails, it's probably related to your change, could you look into it? |
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Seems like we just need to bump the timeout, see #1559 |
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Fixes #1556.
Serena launches rust-analyzer with VS Code's full heavyweight
initializationOptions, hardcoded. On a large, actively-built Rust workspace these drive rust-analyzer to 40+ GB resident and trigger a full re-index on every externalcargo build, even with no editor running. Serena's symbol tools don't need the two eager/auto re-indexing drivers:cachePriming.enable:True→False(no eager whole-workspace + all-deps index — the dominant contributor to the 40 GB resident set)cargo.autoreload:True→False(no re-index storm ontarget// Cargo metadata changes)checkOnSaveis intentionally left enabledIt is tempting to also disable
checkOnSavefor a lightweight profile, but doing so breaksget_diagnostics_for_filefor Rust: rust-analyzer's diagnostics for ordinary errors (e.g. an unresolved name →E0425) come from flycheck (cargo check), and withcheckOnSave: falseSerena's pull-diagnostics request comes back empty —test/solidlsp/rust/test_rust_diagnostics.py::test_file_diagnosticsfails with[].checkOnSaveonly spawns transientcargo checkchild processes and is not a driver of rust-analyzer's resident RSS, so keeping it on preserves diagnostics at no meaningful memory cost.Ideally these would be exposed as a config toggle (per-language
language_server_options, or a globallightweight/symbol_onlyflag) rather than hardcoded, so users who want the full RA feature set can opt in. Happy to rework toward that if preferred.Testing
uv run --extra dev pytest test/solidlsp/rust/→ 26 passed, 5 skipped on Windows 11 (Rust stable 1.95, rust-analyzer from rustup). Bisected to confirmcachePriming/autoreloadare the memory drivers andcheckOnSaveis required for the diagnostics test.