perf(linter/plugins): reduce memory copies for tokens by overlookmotel · Pull Request #19979 · oxc-project/oxc

overlookmotel · 2026-03-03T21:02:28Z

Further optimization after #19978. Reduce memory copies when slicing the tokens array. We can't avoid memory copies entirely, but we can reuse the previous tokens array and avoid them in ~50% of files.

See comment in the code for more details.

overlookmotel · 2026-03-03T21:02:40Z

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

0-merge - adds this PR to the back of the merge queue
hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

_{An organization admin has enabled the Graphite Merge Queue in this repository.} _{Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.}

This stack of pull requests is managed by Graphite. Learn more about stacking.

Sysix · 2026-03-03T21:09:10Z

Where can I learn this witchcraft? It is crazy how much performance you can get out of JS.

Copilot

Pull request overview

Optimizes token deserialization performance in the JS plugin layer by reusing the previously created tokens array when possible, reducing avoidable backing-store copies during initialization.

Changes:

Introduces a previousTokens array cache across files.
Updates initTokens() to reuse/truncate previousTokens when the next file has fewer tokens, otherwise falls back to slice.

overlookmotel · 2026-03-03T22:01:35Z

Where can I learn this witchcraft? It is crazy how much performance you can get out of JS.

LOLs! Same place I did... https://v8.dev/blog and, more recently, chatting with Claude. He writes pretty ropey code IMO, but he knows everything.

graphite-app · 2026-03-03T23:23:30Z

Merge activity

Mar 3, 11:23 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
Mar 3, 11:32 PM UTC: Merged by the Graphite merge queue.

Further optimization after #19978. Reduce memory copies when slicing the tokens array. We can't avoid memory copies entirely, but we can reuse the previous tokens array and avoid them in ~50% of files. See comment in the code for more details.

# Oxlint ### 🚀 Features - e6b604f oxlint: Auto-enable gitlab formatter on GitLab (#20076) (camc314) - 2488a68 linter: Add .oxlintrc.jsonc config file support (#19870) (Scott S.) - 61bf388 linter: Add `options.reportUnusedDisableDirectives` to config file (#19799) (Peter Wagenet) - c92422b oxlint: Auto-enable github formatter on GitHub Actions (#19944) (Boshen) - 0337c6d linter: Implement typescript/no-unecessary-type-conversion (#19955) (camc314) - 2919313 linter: Introduce denyWarnings config options (#19926) (camc314) - a607119 linter: Introduce maxWarnings config option (#19777) (camc314) ### 🐛 Bug Fixes - 0861d9a linter/plugins: Remove getters from `Context` (#20115) (overlookmotel) - 92cfb14 linter/plugins: Fix types for `walkProgram` and `walkProgramWithCfg` (#20081) (overlookmotel) - 10e211f oxlint/lsp: Send other code actions besides `source.fixAll` if requested (#20042) (Sysix) - 602daaa linter/plugins: Fix type definition for `VisitorObject` (#20065) (overlookmotel) - ee0491e apps,napi: Explicitly specify libs in tsconfigs (#20071) (camc314) - b6e9499 linter: Fix the logic for `unicorn/prefer-dom-node-remove` to handle literal callees as well as arguments. (#20059) (connorshea) - 3874ae1 linter: Update `unicorn/prefer-query-selector` to also catch `getElementsByName()`. (#20060) (connorshea) - 77c93fb linter: Handle array-type shorthand inside union members (#20034) (camc314) - 50eb160 linter/no-unused-vars: Allow unused type params in ambient module blocks (#19615) (Don Isaac) - 1dd0d21 linter/no-restricted-imports: Apply regex pattern checks to side-effect imports (#20028) (camc314) - 7f3d735 linter: Error when --type-check is used without --type-aware (#20025) (camc314) - eea201c unicorn/prefer-string-slice: Avoid unsafe autofix for substr-to-slice (#20010) (camc314) - 50359dc oxlint/lsp: Detect `reportUnusedDisableDirectives` from oxlint config, change lsp `unusedDisableDirectives` default value to `None` (#20011) (Sysix) - 4bc84b1 linter/plugins: Allow `null` and `undefined` for `rule.meta.fixable` (#20008) (overlookmotel) - 753e27e linter/role-supports-aria-props: Add `aria-posinset` to supported `option` ARIA properties (#20003) (JongKyung Lee) - f57b2c9 linter/plugins: Fix return types of tokens methods (#19985) (overlookmotel) - 27ee4fc linter/no-loss-of-precision: Avoid double rounding for negative exponents (#19999) (camc314) - 77a94bb linter: Avoid no-loss-of-precision false positive for 3e-308 (#19992) (camc314) - 6245c56 linter/no-unused-private-class-members: Treat logical lhs access as usage (#19991) (camc314) - 65891e3 linter: Avoid prefer-const false positive for mixed-scope destructuring (#19982) (camc314) - 89991fe linter: Avoid prefer-const false positive for operator reassignments (#19975) (camc314) - 87318e7 oxlint/lsp: Load js config with reforcing fs read (#19551) (Sysix) - d40a942 linter/no-useless-constructor: Mark fixer as suggestion (#19961) (camc314) - ccbd959 linter/prefer-code-point: Report String.fromCharCode member references (#19931) (camc314) - 14fbbfc linter: Add help text to oxc/no-rest-spread-properties rule (#19900) (Subin Kim) ### ⚡ Performance - 2baa5fb napi: Unify build-test profile to coverage for cache sharing (#20090) (Boshen) - 77f1c71 linter/plugins: Make tokens class instances (#19980) (overlookmotel) - 758b424 linter/plugins: Reduce memory copies for tokens (#19979) (overlookmotel) - 236847f linter/plugins: Cache token objects (#19978) (overlookmotel) - 94b597a linter/plugins: Store tokens as a `Box<[Token]>` (#19969) (overlookmotel) ### 📚 Documentation - 2c0010a linter/plugins: Move comment about "bivariance hack" into generated code (#20082) (overlookmotel) - 7538f09 linter: Improve `import/extensions` and `import/no-named-as-default` rule docs. (#20053) (connorshea) - 1f909cf linter: Improve docs for `unicorn/require-post-message-target-origin` rule. (#20061) (connorshea) - 12ae35c oxlint/lsp: Remove outdated ToDo for `LintOptions.run` (#20012) (Sysix) - 3be73e6 linter/plugins: Fix JSDoc comments for tokens methods (#20004) (overlookmotel) - 48ef285 linter: Update `--config` docs (#19965) (camc314) - 6ea49a0 linter: Fix some identation issues for the generated types used in `oxlint.config.ts`. (#19942) (connorshea) - 6c0e0b5 linter: Add oxlint.config.ts to the config docs. (#19941) (connorshea) - 160e423 linter: Add a note that the typeAware and typeCheck options require oxlint-tsgolint (#19940) (connorshea) - d54c275 linter: Improve rule docs for 27 unicorn rules (#19903) (connorshea) # Oxfmt ### 🚀 Features - ee26215 oxfmt: Support css-in-js substitution (#20019) (leaysgur) - 0f0ff51 oxfmt: Display default settings was used message in cli stats (#19939) (leaysgur) - 88815b8 oxfmt: Reintroduce stats line for write mode (#19938) (leaysgur) ### 🐛 Bug Fixes - ee0491e apps,napi: Explicitly specify libs in tsconfigs (#20071) (camc314) - 92f4490 oxfmt: Apply `is_ignored_dir` for glob paths too (#20056) (leaysgur) - 114f974 oxfmt/lsp: Prefer language_id over file extension when formatting (#19977) (copilot-swe-agent) ### ⚡ Performance - 2baa5fb napi: Unify build-test profile to coverage for cache sharing (#20090) (Boshen) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

overlookmotel mentioned this pull request Mar 3, 2026

perf(linter/plugins): cache token objects #19978

Merged

github-actions bot added A-linter Area - Linter A-cli Area - CLI A-linter-plugins Area - Linter JS plugins labels Mar 3, 2026

overlookmotel mentioned this pull request Mar 3, 2026

perf(linter/plugins): make tokens class instances #19980

Merged

github-actions bot added the C-performance Category - Solution not expected to change functional behavior, only performance label Mar 3, 2026

overlookmotel mentioned this pull request Mar 3, 2026

refactor(linter/plugins): split tokens initialization from tokens methods #19981

Merged

overlookmotel marked this pull request as ready for review March 3, 2026 21:08

overlookmotel requested a review from camc314 as a code owner March 3, 2026 21:08

Copilot AI review requested due to automatic review settings March 3, 2026 21:08

Copilot started reviewing on behalf of overlookmotel March 3, 2026 21:09 View session

Copilot AI reviewed Mar 3, 2026

View reviewed changes

camc314 assigned overlookmotel Mar 3, 2026

overlookmotel force-pushed the om/03-02-perf_linter_plugins_cache_token_objects branch from dbf5724 to 0aa0c02 Compare March 3, 2026 22:42

overlookmotel force-pushed the om/03-02-perf_linter_plugins_reduce_memory_copies_for_tokens branch from 5338b5c to c477205 Compare March 3, 2026 22:42

graphite-app bot added the 0-merge Merge with Graphite Merge Queue label Mar 3, 2026

graphite-app bot force-pushed the om/03-02-perf_linter_plugins_cache_token_objects branch from 0aa0c02 to 236847f Compare March 3, 2026 23:23

graphite-app bot force-pushed the om/03-02-perf_linter_plugins_reduce_memory_copies_for_tokens branch from c477205 to 758b424 Compare March 3, 2026 23:24

Base automatically changed from om/03-02-perf_linter_plugins_cache_token_objects to main March 3, 2026 23:31

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Mar 3, 2026

graphite-app bot merged commit 758b424 into main Mar 3, 2026
20 checks passed

graphite-app bot deleted the om/03-02-perf_linter_plugins_reduce_memory_copies_for_tokens branch March 3, 2026 23:32

Boshen mentioned this pull request Mar 9, 2026

release(apps): oxlint v1.52.0 && oxfmt v0.37.0 #20143

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

perf(linter/plugins): reduce memory copies for tokens#19979

perf(linter/plugins): reduce memory copies for tokens#19979
graphite-app[bot] merged 1 commit intomainfrom
om/03-02-perf_linter_plugins_reduce_memory_copies_for_tokens

overlookmotel commented Mar 3, 2026 •

edited

Loading

Uh oh!

overlookmotel commented Mar 3, 2026 •

edited

Loading

Uh oh!

Sysix commented Mar 3, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

overlookmotel commented Mar 3, 2026

Uh oh!

graphite-app bot commented Mar 3, 2026 •

edited

Loading

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

overlookmotel commented Mar 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

overlookmotel commented Mar 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

How to use the Graphite Merge Queue

Uh oh!

Sysix commented Mar 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

overlookmotel commented Mar 3, 2026

Uh oh!

graphite-app bot commented Mar 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merge activity

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

overlookmotel commented Mar 3, 2026 •

edited

Loading

overlookmotel commented Mar 3, 2026 •

edited

Loading

Sysix commented Mar 3, 2026 •

edited

Loading

graphite-app bot commented Mar 3, 2026 •

edited

Loading