stream: fold desired-size check into WHATWG backpressure update by mcollina · Pull Request #64451 · nodejs/node

mcollina · 2026-07-12T15:12:39Z

writableStreamUpdateBackpressure ran two release-mode assertions and took a precomputed backpressure value that every caller derived with a separate GetBackpressure/GetDesiredSize call pair. All callers already hold the writable, not-close-queued invariant the assertions checked, so the backpressure is now derived from the desired size inside the function, dropping the assertions and the helper. This runs up to twice per write.

writer.write() loop: +10% (local harness)
pipe-to: +4.6% avg over 16 configs, all positive (benchmark, 20 runs)

The first commit is #64431; only the last commit is new here.

The [[queue]] backing the controllers became a ring buffer, but the read and write request queues (readRequests, readIntoRequests, writeRequests) were left as plain arrays consumed with ArrayPrototypeShift, which is O(n) and, even for the single pending request of the await-each regime, far slower than an indexed head advance. Back them with the same Queue, materialized lazily from the shared empty queue so acquiring a reader or constructing a writer allocates no request storage until a read or write actually parks. pipe-to: +4.7% to +9.4% (all 16 configs, ***) readable-read type=byob: +2.3% (**) parked read loop: +15%, write loop: +11% (local harness) Follow-up to nodejs#64312. Signed-off-by: Matteo Collina <hello@matteocollina.com>

writableStreamUpdateBackpressure ran two release-mode assertions and took a precomputed backpressure value that every caller derived with a separate GetBackpressure/GetDesiredSize call pair. All callers already hold the 'writable', not-close-queued invariant the assertions checked, so derive the backpressure from the desired size inside the function and drop the assertions and the helper. This runs up to twice per write. writer.write() loop: +10%, pipe-to: +4.6% avg over 16 configs (local harness / benchmark, all configs positive). Signed-off-by: Matteo Collina <hello@matteocollina.com>

codecov · 2026-07-12T17:00:30Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.24%. Comparing base (8a3b11c) to head (3cb9f68).
⚠️ Report is 45 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #64451 +/- ##
==========================================
- Coverage 90.24% 90.24% -0.01% 
==========================================
Files 741 741 Lines 241384 241610 +226 Branches 45480 45519 +39 ==========================================
+ Hits 217844 218041 +197 - Misses 15097 15110 +13 - Partials 8443 8459 +16

Files with missing lines	Coverage Δ
lib/internal/webstreams/readablestream.js	`98.19% <100.00%> (+<0.01%)`	⬆️
lib/internal/webstreams/util.js	`97.71% <100.00%> (+<0.01%)`	⬆️
lib/internal/webstreams/writablestream.js	`99.50% <100.00%> (-0.01%)`	⬇️

... and 47 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-07-13T20:49:57Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74797/

mcollina · 2026-07-14T13:41:52Z

@trivikr can you review?

trivikr

lgtm

nodejs-github-bot · 2026-07-16T06:41:31Z

Commit Queue failed

- Loading data for nodejs/node/pull/64451 ✔ Done loading data for nodejs/node/pull/64451 ----------------------------------- PR info ------------------------------------ Title stream: fold desired-size check into WHATWG backpressure update (#64451) Author Matteo Collina <matteo.collina@gmail.com> (@mcollina) Branch mcollina:webstream-perf-round9 -> nodejs:main Labels author ready, needs-ci, web streams Commits 2 - stream: use the ring buffer for WHATWG stream request queues - stream: fold desired-size check into WHATWG backpressure update Committers 1 - Matteo Collina <hello@matteocollina.com> PR-URL: https://github.com/nodejs/node/pull/64451 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/64451 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> -------------------------------------------------------------------------------- ℹ This PR was created on Sun, 12 Jul 2026 15:12:39 GMT ✔ Approvals: 2 ✔ - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/64451#pullrequestreview-4680407396 ✔ - Trivikram Kamat (@trivikr): https://github.com/nodejs/node/pull/64451#pullrequestreview-4710339944 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2026-07-13T20:49:57Z: https://ci.nodejs.org/job/node-test-pull-request/74797/ - Querying data for job/node-test-pull-request/74797/ ✔ Build data downloaded ✔ Last Jenkins CI successful -------------------------------------------------------------------------------- ✔ No git cherry-pick in progress ✔ No git am in progress ✔ No git rebase in progress -------------------------------------------------------------------------------- - Bringing origin/main up to date... From https://github.com/nodejs/node * branch main -> FETCH_HEAD 608112affa..874e96ee4c main -> origin/main ✔ origin/main is now up-to-date main is out of sync with origin/main. Mismatched commits: - d91a9207a0 stream: validate writer options signal - 874e96ee4c stream: validate writer options signal -------------------------------------------------------------------------------- HEAD is now at 874e96ee4c stream: validate writer options signal ✔ Reset to origin/main - Downloading patch for 64451 From https://github.com/nodejs/node * branch refs/pull/64451/merge -> FETCH_HEAD ✔ Fetched commits as 608112affae2..3cb9f689c486 -------------------------------------------------------------------------------- The previous cherry-pick is now empty, possibly due to conflict resolution. If you wish to commit it anyway, use:

git commit --allow-empty

Otherwise, please use 'git cherry-pick --skip'
On branch main
Your branch is up to date with 'origin/main'.

You are currently cherry-picking commit e65f9befaf.
(all conflicts fixed: run "git cherry-pick --continue")
(use "git cherry-pick --skip" to skip this patch)
(use "git cherry-pick --abort" to cancel the cherry-pick operation)

Untracked files:
(use "git add <file>..." to include in what will be committed)
labels.json
output

nothing added to commit but untracked files present (use "git add" to track)
✘ Failed to apply patches

https://github.com/nodejs/node/actions/runs/29477179597

nodejs-github-bot · 2026-07-16T08:26:35Z

Commit Queue failed

- Loading data for nodejs/node/pull/64451 ✔ Done loading data for nodejs/node/pull/64451 ----------------------------------- PR info ------------------------------------ Title stream: fold desired-size check into WHATWG backpressure update (#64451) Author Matteo Collina <matteo.collina@gmail.com> (@mcollina) Branch mcollina:webstream-perf-round9 -> nodejs:main Labels author ready, needs-ci, web streams, commit-queue-squash Commits 2 - stream: use the ring buffer for WHATWG stream request queues - stream: fold desired-size check into WHATWG backpressure update Committers 1 - Matteo Collina <hello@matteocollina.com> PR-URL: https://github.com/nodejs/node/pull/64451 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/64451 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> -------------------------------------------------------------------------------- ℹ This PR was created on Sun, 12 Jul 2026 15:12:39 GMT ✔ Approvals: 2 ✔ - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/64451#pullrequestreview-4680407396 ✔ - Trivikram Kamat (@trivikr): https://github.com/nodejs/node/pull/64451#pullrequestreview-4710339944 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2026-07-16T06:41:31Z: https://ci.nodejs.org/job/node-test-pull-request/74797/ - Querying data for job/node-test-pull-request/74797/ ✔ Build data downloaded ✔ Last Jenkins CI successful -------------------------------------------------------------------------------- ✔ No git cherry-pick in progress ✔ No git am in progress ✔ No git rebase in progress -------------------------------------------------------------------------------- - Bringing origin/main up to date... From https://github.com/nodejs/node * branch main -> FETCH_HEAD ✔ origin/main is now up-to-date - Downloading patch for 64451 From https://github.com/nodejs/node * branch refs/pull/64451/merge -> FETCH_HEAD ✔ Fetched commits as 608112affae2..3cb9f689c486 -------------------------------------------------------------------------------- The previous cherry-pick is now empty, possibly due to conflict resolution. If you wish to commit it anyway, use:

git commit --allow-empty

Otherwise, please use 'git cherry-pick --skip'
On branch main
Your branch is up to date with 'origin/main'.

You are currently cherry-picking commit e65f9befaf.
(all conflicts fixed: run "git cherry-pick --continue")
(use "git cherry-pick --skip" to skip this patch)
(use "git cherry-pick --abort" to cancel the cherry-pick operation)

Untracked files:
(use "git add <file>..." to include in what will be committed)
labels.json
output

nothing added to commit but untracked files present (use "git add" to track)
✘ Failed to apply patches

https://github.com/nodejs/node/actions/runs/29483233622

aduh95 · 2026-07-16T11:34:11Z

Landed in cf882a7

writableStreamUpdateBackpressure ran two release-mode assertions and took a precomputed backpressure value that every caller derived with a separate GetBackpressure/GetDesiredSize call pair. All callers already hold the 'writable', not-close-queued invariant the assertions checked, so derive the backpressure from the desired size inside the function and drop the assertions and the helper. This runs up to twice per write. writer.write() loop: +10%, pipe-to: +4.6% avg over 16 configs (local harness / benchmark, all configs positive). Signed-off-by: Matteo Collina <hello@matteocollina.com> PR-URL: #64451 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

mcollina added 2 commits July 12, 2026 12:48

nodejs-github-bot added needs-ci PRs that need a full CI run. web streams labels Jul 12, 2026

jasnell approved these changes Jul 12, 2026
View reviewed changes

mcollina added the request-ci Add this label to start a Jenkins CI on a PR. label Jul 13, 2026

github-actionsBot removed the request-ci Add this label to start a Jenkins CI on a PR. label Jul 13, 2026

This comment was marked as outdated.
Sign in to view

trivikr added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Jul 14, 2026

trivikr approved these changes Jul 16, 2026
View reviewed changes

mcollina added the commit-queue Add this label to land a pull request using GitHub Actions. label Jul 16, 2026

nodejs-github-bot added commit-queue-failed An error occurred while landing this pull request using GitHub Actions. and removed commit-queue Add this label to land a pull request using GitHub Actions. labels Jul 16, 2026

aduh95 merged commit cf882a7 into nodejs:mainJul 16, 2026
100 checks passed

github-actionsBot mentioned this pull request Jul 21, 2026
2026-07-22, Version 26.6.0 (Current) #64655
Merged

mcollina mentioned this pull request Jul 29, 2026
stream: reduce per-chunk work in WHATWG tee and BYOB reads #64818
Merged

Navigation Menu

Uh oh!

Uh oh!

stream: fold desired-size check into WHATWG backpressure update - #64451

stream: fold desired-size check into WHATWG backpressure update#64451
aduh95 merged 2 commits into
nodejs:mainfrom
mcollina:webstream-perf-round9

mcollina commented Jul 12, 2026

Uh oh!

codecovBot commented Jul 12, 2026•
edited
Loading

Uh oh!

This comment was marked as outdated.

nodejs-github-bot commented Jul 13, 2026

Uh oh!

mcollina commented Jul 14, 2026

Uh oh!

trivikr left a comment

Uh oh!

nodejs-github-bot commented Jul 16, 2026

Uh oh!

nodejs-github-bot commented Jul 16, 2026

Uh oh!

Uh oh!

aduh95 commented Jul 16, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Uh oh!

Uh oh!

Conversation

mcollina commented Jul 12, 2026

Uh oh!

codecovBot commented Jul 12, 2026• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

This comment was marked as outdated.

nodejs-github-bot commented Jul 13, 2026

Uh oh!

mcollina commented Jul 14, 2026

Uh oh!

trivikr left a comment

Choose a reason for hiding this comment

Uh oh!

nodejs-github-bot commented Jul 16, 2026

Uh oh!

nodejs-github-bot commented Jul 16, 2026

Uh oh!

Uh oh!

aduh95 commented Jul 16, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

codecovBot commented Jul 12, 2026•
edited
Loading