perf(net): avoid redundant chunk copies and plan performance investigations by kixelated · Pull Request #3443 · moq-dev/moq

kixelated · 2026-09-05T06:42:55Z

Summary

Remove the intermediate incoming-chunk copy when the JS Reader joins buffered data. The combined buffer already owns a copy, so the extra allocation adds work without improving isolation. Add coverage for subarray offsets, input mutation, and retained output views.
Add six scoped quests for fragmented reader buffering, shared traffic-counter contention, CMAF copies, CPU/allocation profiling, repeatable benchmark comparisons, and browser benchmarks. Each names source evidence, workloads, metrics, and acceptance criteria.

A local allocation probe assembling 1 MiB from sixteen 64 KiB chunks dropped from 31 to 16 payload allocations, removing 960 KiB of temporary copying. Wall-clock samples were too noisy to claim a speedup.

Public API changes

None. No package versions change.

Wire behavior changes

None. Decoded bytes, buffering ownership, errors, and delivery semantics are preserved. Rust/API/spec synchronization is unnecessary for this internal JS allocation change.

Test plan

just fix origin/main, just check origin/main, and just test default origin/main passed locally using Nix-provided Bun 1.3.13. The full Nix shell was unavailable due to stalled startup; CI covers the complete pinned toolchain.
The targeted net suite passed 508 tests on the main-base code; subsequent changes only correct quest references and clarify overlap with existing work.
Quest validation passed all 253 documents. git diff --check origin/main...HEAD passed.
CI Check and Test passed on final head 18b1f6fa5. The local test recipe passed 1,100 tests.

(written by GPT-6)

…ations Co-Authored-By: GPT-6 <noreply@openai.com>

coderabbitai · 2026-09-05T06:43:05Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Team

Run ID: 822190a0-e835-42ed-a147-273a494a2c2b

📥 Commits

Reviewing files that changed from the base of the PR and between 84ee98b and 18b1f6f.

📒 Files selected for processing (9)

js/net/src/stream.test.ts
js/net/src/stream.ts
quest/m2/README.md
quest/m2/browser-benchmarks.md
quest/m2/cmaf-copy-budget.md
quest/m2/performance-comparisons.md
quest/m2/performance-profiles.md
quest/m2/stats-contention.md
quest/m2/stream-buffering.md

Included review availability: Your plan provides up to 4 included reviews per hour; 0 remain after this review.

Walkthrough

The change updates Reader.#fill to avoid an eager copy when its internal buffer is empty. A test verifies chunk ownership and returned-view isolation. The m2 quest index adds six performance entries. New quest documents define plans for benchmark comparison, relay profiling, browser benchmarks, stream buffering, traffic-counter contention, and CMAF copy measurement.

Merge Risk: ⚪ Minimal · up to 18b1f

This change reduces temporary Reader copying while preserving buffer isolation through targeted tests, and adds performance-planning documentation. No current merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly summarizes both main changes: removing redundant network chunk copies and adding performance investigation plans.
Description check	✅ Passed	The description directly explains the Reader allocation change, test coverage, added quests, measured results, and validation status.

✨ Finishing Touches

✨ Simplify code

Create PR with simplified code
Commit simplified code in branch codex/performance-survey

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kixelated · 2026-09-05T06:45:52Z

@codex review

(written by GPT-6)

kixelated · 2026-09-05T06:45:53Z

@coderabbitai full review

(written by GPT-6)

coderabbitai · 2026-09-05T06:46:06Z

@kixelated I will perform a complete review of PR #3443.

⚠️ Action not completed

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chatgpt-codex-connector · 2026-09-05T06:46:09Z

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-05T06:58:08.248782Z	`18b1f6f`	Manual request

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💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 414d232cf1

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Co-Authored-By: GPT-6 <noreply@openai.com>

kixelated · 2026-09-05T06:54:34Z

@codex review

Please review head 18b1f6f, which corrects the quest paths reported in the previous review.

(written by GPT-6)

chatgpt-codex-connector · 2026-09-05T06:58:06Z

Codex Review: Didn't find any major issues. Bravo.

Reviewed commit: 18b1f6fa52

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Open a pull request for review
Mark a draft as ready
Comment "@codex review".

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kixelated · 2026-09-05T06:58:27Z

@coderabbitai full review

Retrying after the stated quota reset. Please review head 18b1f6f; the benchmark and profiler quest references now match main.

(written by GPT-6)

coderabbitai · 2026-09-05T06:58:42Z

@kixelated I will perform a complete review of PR #3443 at head 18b1f6fa5.

✅ Action performed

Full review finished.

* docs(quest): settle scope narrowing in place, and mark pre-media sidecar placement (moq-dev#3427) Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> * fix(moq-video): pick the V4L2 mode nearest the requested resolution (moq-dev#3355) Co-authored-by: Luke Curley <kixelated@gmail.com> Co-authored-by: Codex <codex@openai.com> * feat(moq-video): add the Android MediaCodec encoder and decoder (moq-dev#3354) Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com> Co-authored-by: Luke Curley <kixelated@gmail.com> * docs(quest): import the post-grooming issues as quests (moq-dev#3431) Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> * docs(quest): apply the Codex findings on the issue import (moq-dev#3432) Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> * fix(claude): adopt a quest branch at the remote tip that was inspected (moq-dev#3421) Co-authored-by: Claude Opus 5 <noreply@anthropic.com> * docs(quest): record four findings from the m1 quest wave (moq-dev#3424) Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com> * docs: reorganize the site around what a reader can do (moq-dev#3426) Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> * chore: ignore Claude Code's scratch directories (moq-dev#3428) Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com> * chore(moq-audio,moq-cli): assert publish_capture stays Send off macOS (moq-dev#3433) Co-authored-by: Claude Opus 5 <noreply@anthropic.com> * docs: correct claims found during merge review (moq-dev#3435) Co-authored-by: GPT-5 <noreply@openai.com> * docs(quest): import the open issues that had no quest, and gate the dev merge (moq-dev#3434) Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> * docs(moq-audio): scope the local-task guidance to macOS (moq-dev#3436) Co-authored-by: Claude Opus 5 <noreply@anthropic.com> * docs: track deferred review findings (moq-dev#3438) Co-authored-by: GPT-5 <noreply@openai.com> * chore: remove redundant packaging work and plan relay ownership fixes (moq-dev#3440) Co-authored-by: GPT-6 <noreply@openai.com> * perf(net): avoid redundant chunk copies and plan performance investigations (moq-dev#3443) Co-authored-by: GPT-6 <noreply@openai.com> * fix(transcode): follow a source resolution change with the ladder (moq-dev#3381) Co-authored-by: Claude Opus 5 <noreply@anthropic.com> Co-authored-by: GPT-5 <noreply@openai.com> * feat(watch): share one AudioContext across audio decoders Spatial playback needs every remote in the same Web Audio graph. Injected contexts are never closed. Co-Authored-By: Cursor Grok 4.6 <noreply@cursor.com> Co-authored-by: Cursor <cursoragent@cursor.com> --------- Co-authored-by: Luke Curley <kixelated@gmail.com> Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> Co-authored-by: Franz Heinzmann <frando@unbiskant.org> Co-authored-by: Codex <codex@openai.com> Co-authored-by: GPT-5 <noreply@openai.com> Co-authored-by: Cursor Grok 4.6 <noreply@cursor.com> Co-authored-by: Cursor <cursoragent@cursor.com>

perf(net): avoid redundant chunk copies and plan performance investig…

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…ations Co-Authored-By: GPT-6 <noreply@openai.com>

chatgpt-codex-connector Bot reviewed Sep 5, 2026

View reviewed changes

Comment thread quest/m2/performance-profiles.md Outdated

docs(quest): align performance plans with main

18b1f6f

Co-Authored-By: GPT-6 <noreply@openai.com>

kixelated merged commit f823668 into main Sep 5, 2026
2 checks passed

kixelated deleted the codex/performance-survey branch September 5, 2026 07:05

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perf(net): avoid redundant chunk copies and plan performance investigations - #3443

perf(net): avoid redundant chunk copies and plan performance investigations#3443
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