feat: add a trace for renderMainThread by HuJean · Pull Request #2398 · lynx-family/lynx-stack

HuJean · 2026-03-30T07:15:54Z

Summary by CodeRabbit

Chores
- Added a changeset metadata file.
- Improved internal profiling instrumentation to better track rendering and rendering-stage performance.

Checklist

Tests updated (or not required).
Documentation updated (or not required).
Changeset added, and when a BREAKING CHANGE occurs, it needs to be clearly marked (or not required).

changeset-bot · 2026-03-30T07:15:59Z

🦋 Changeset detected

Latest commit: cf3d912

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 0 packages

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coderabbitai · 2026-03-30T07:16:09Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: ea980a4f-da78-4c7d-ba9c-223e0535c55e

📥 Commits

Reviewing files that changed from the base of the PR and between 9b0c38b and cf3d912.

📒 Files selected for processing (2)

.changeset/itchy-dogs-search.md
packages/react/runtime/src/lifecycle/render.ts

✅ Files skipped from review due to trivial changes (1)

.changeset/itchy-dogs-search.md

🚧 Files skipped from review as they are similar to previous changes (1)

packages/react/runtime/src/lifecycle/render.ts

📝 Walkthrough

Walkthrough

Added an empty Changeset markdown file and modified renderMainThread() in the React runtime to add conditional profiling start/end calls, resulting in a duplicated conditional profileEnd() in addition to the existing profileEnd() in the finally block.

Changes

Cohort / File(s)	Summary
Changesets `.changeset/itchy-dogs-search.md`	Added a new Changeset markdown file containing only YAML frontmatter markers (`---` ... `---`) with no version or content fields.
React Runtime Profiling `packages/react/runtime/src/lifecycle/render.ts`	Inserted a conditional `profileStart('ReactLynx::renderMainThread')` before the `try`, changed an inner `profileStart` tag to `ReactLynx::renderToString`, and added an extra conditional `profileEnd()` after the render pipeline, duplicating the existing `profileEnd()` in the `finally`.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

refactor(react/runtime): use lynx.performance.profileStart #1533: Modifies profiling instrumentation in renderMainThread() with similar changes to profileStart/profileEnd usage.

Suggested reviewers

Yradex
hzy

Poem

🐰 I hop in code, a curious sight,

I mark the starts and ends just right,
Two little ends now join the run,
Timing dances under sun,
Hooray — the render race is fun! 🥕

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: add a trace for renderMainThread' directly matches the main objective of the PR and accurately describes the primary change to the renderMainThread function.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

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Commit unit tests in branch p/perf-trace

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codecov · 2026-03-30T07:18:22Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/react/runtime/src/lifecycle/render.ts`:
- Around line 18-20: The duplicate profiling span should be removed and the
existing ReactLynx::renderMainThread trace (created via profileStart/profileEnd)
should be expanded to cover the entire renderMainThread function; move the
single profileStart to the outermost entry of renderMainThread and wrap the
function body in a try/finally that always calls profileEnd, removing the inner
profileStart/profileEnd pair that currently encloses renderOpcodesInto() and the
test-only opcode remap so the trace is not nested or left unbalanced if remap or
renderOpcodesInto() throws.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 53087848-02b1-40a7-be07-67e2acc6b84e

📥 Commits

Reviewing files that changed from the base of the PR and between 78493b4 and 9b0c38b.

📒 Files selected for processing (2)

.changeset/itchy-dogs-search.md
packages/react/runtime/src/lifecycle/render.ts

coderabbitai · 2026-03-30T07:23:05Z

+  if (typeof __PROFILE__ !== 'undefined' && __PROFILE__) {
+    profileStart('ReactLynx::renderMainThread');
+  }


⚠️ Potential issue | 🟠 Major

Expand the existing renderMainThread trace instead of adding a second one.

Lines 23-33 already manage a ReactLynx::renderMainThread span. Adding another start here and another end on Line 58 nests the same trace name, and the new outer end is skipped if the test-only opcode remap or renderOpcodesInto() throws. Since profileEnd just forwards to the native profiler, that can leave profiling state unbalanced and pollute later measurements. If the intent is to cover the whole function, widen the current trace to a single outer try/finally and drop the inner duplicate.

Also applies to: 57-59

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed. In `@packages/react/runtime/src/lifecycle/render.ts` around lines 18 - 20, The duplicate profiling span should be removed and the existing ReactLynx::renderMainThread trace (created via profileStart/profileEnd) should be expanded to cover the entire renderMainThread function; move the single profileStart to the outermost entry of renderMainThread and wrap the function body in a try/finally that always calls profileEnd, removing the inner profileStart/profileEnd pair that currently encloses renderOpcodesInto() and the test-only opcode remap so the trace is not nested or left unbalanced if remap or renderOpcodesInto() throws.

codspeed-hq · 2026-03-30T07:32:41Z

Merging this PR will degrade performance by 66.25%

⚡ 1 improved benchmark
❌ 5 regressed benchmarks
✅ 62 untouched benchmarks
⏩ 25 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	`BASE`	`HEAD`	Efficiency
❌	`006-static-raw-text__main-thread-renderMainThread`	1.8 ms	5.3 ms	-66.25%
❌	`003-hello-list__main-thread-renderMainThread`	16.6 ms	19.1 ms	-12.92%
❌	`002-hello-reactLynx__main-thread-renderMainThread`	2.2 ms	4 ms	-44.97%
⚡	`002-hello-reactLynx-destroyBackground`	861.5 µs	680.1 µs	+26.69%
❌	`007-four-layer-views__main-thread-renderMainThread`	185.1 ms	402.8 ms	-54.05%
❌	`transform 1000 view elements`	40.4 ms	47.3 ms	-14.74%

_{Comparing p/perf-trace (cf3d912) with main (78493b4)}

25 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

relativeci · 2026-03-30T07:38:08Z

React MTF Example

#89 Bundle Size — 207.47KiB (0%).

cf3d912(current) vs 78493b4 main#76(baseline)

Bundle metrics no changes

	Current #89	Baseline #76
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`0%`	`0%`
Chunks	`0`	`0`
Assets	`3`	`3`
Modules	`174`	`174`
Duplicate Modules	`68`	`68`
Duplicate Code	`46.09%`	`46.09%`
Packages	`2`	`2`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #89	Baseline #76
IMG	`111.23KiB`	`111.23KiB`
Other	`96.24KiB`	`96.24KiB`

Bundle analysis report Branch p/perf-trace Project dashboard

^{Generated by RelativeCI Documentation Report issue}

relativeci · 2026-03-30T07:38:09Z

React Example

#6955 Bundle Size — 237.89KiB (0%).

cf3d912(current) vs 78493b4 main#6942(baseline)

Bundle metrics no changes

	Current #6955	Baseline #6942
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`0%`	`0%`
Chunks	`0`	`0`
Assets	`4`	`4`
Modules	`180`	`180`
Duplicate Modules	`71`	`71`
Duplicate Code	`46.4%`	`46.4%`
Packages	`2`	`2`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #6955	Baseline #6942
IMG	`145.76KiB`	`145.76KiB`
Other	`92.13KiB`	`92.13KiB`

Bundle analysis report Branch p/perf-trace Project dashboard

^{Generated by RelativeCI Documentation Report issue}

relativeci · 2026-03-30T07:38:11Z

Web Explorer

#8533 Bundle Size — 728.6KiB (0%).

cf3d912(current) vs 78493b4 main#8520(baseline)

Bundle metrics

1 change

	Current #8533	Baseline #8520
Initial JS	`43.3KiB`	`43.3KiB`
Initial CSS	`2.16KiB`	`2.16KiB`
Cache Invalidation	`0%`	`0%`
Chunks	`8`	`8`
Assets	`10`	`10`
Modules	`148`	`148`
Duplicate Modules	`11`	`11`
Duplicate Code	`34.69%`(`-0.03%`)	`34.7%`
Packages	`3`	`3`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #8533	Baseline #8520
Other	`384.4KiB`	`384.4KiB`
JS	`342.04KiB`	`342.04KiB`
CSS	`2.16KiB`	`2.16KiB`

Bundle analysis report Branch p/perf-trace Project dashboard

^{Generated by RelativeCI Documentation Report issue}

HuJean requested review from Yradex and hzy as code owners March 30, 2026 07:15

coderabbitai Bot added the framework:React label Mar 30, 2026

coderabbitai Bot reviewed Mar 30, 2026

View reviewed changes

feat: add a trace for renderMainThread

cf3d912

HuJean force-pushed the p/perf-trace branch from 9b0c38b to cf3d912 Compare March 30, 2026 08:45

HuJean closed this Mar 31, 2026

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feat: add a trace for renderMainThread#2398

feat: add a trace for renderMainThread#2398
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Merging this PR will degrade performance by 66.25%

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