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perf_hooks: add options to monitorEventLoopDelay() - #66115

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jasnell:jasnell/perf-hooks-eld-range-options
Sep 27, 2026
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perf_hooks: add options to monitorEventLoopDelay()#66115
nodejs-github-bot merged 4 commits into
nodejs:mainfrom
jasnell:jasnell/perf-hooks-eld-range-options

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@jasnell jasnell commented Sep 18, 2026

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Adds options to tune histogram parameters to monitorEventLoopDelay()

Also fix a truncation and doc bug.

@jasnell jasnell added semver-minor PRs that contain new features and should be released in the next minor version. perf_hooks Issues and PRs related to the perf_hooks module and performance measurement APIs. labels Sep 18, 2026
@nodejs-github-bot nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs involving general changes in the lib/ or src/ directories. needs-ci PRs that need a full CI run. labels Sep 18, 2026
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Codecov Report

❌ Patch coverage is 85.71429% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.37%. Comparing base (9c06dab) to head (0e5e587).
⚠️ Report is 35 commits behind head on main.

Files with missing lines Patch % Lines
src/node_perf.cc 58.82% 0 Missing and 7 partials ⚠️
Additional details and impacted files 
@@            Coverage Diff             @@
##             main   #66115      +/-   ##
==========================================
- Coverage   90.37%   90.37%   -0.01%     
==========================================
  Files         790      792       +2     
  Lines      274272   275340    +1068     
  Branches    52502    52769     +267     
==========================================
+ Hits       247865   248830     +965     
- Misses      16890    16924      +34     
- Partials     9517     9586      +69
Files with missing lines Coverage Δ
lib/internal/histogram.js 97.52% <100.00%> (+<0.01%) ⬆️
lib/internal/perf/event_loop_delay.js 95.90% <100.00%> (+1.00%) ⬆️
src/histogram.cc 86.67% <100.00%> (-0.14%) ⬇️
src/histogram.h 84.31% <ø> (ø)
src/node_perf.cc 86.11% <58.82%> (-1.85%) ⬇️

... and 61 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.

@jasnell
perf_hooks: fix truncation of monitorEventLoopDelay() resolution
692a3a8 
`IntervalHistogram` stored the interval as `int32_t`, so a resolution
above 2^31 - 1 ms wrapped: `resolution: 2 ** 32 + 1` sampled every
millisecond.

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
@jasnell
doc: fix description of histogram.exceeds
468ca5c 
It counts values above the highest recordable value, for every
histogram type. Event loop delay histograms no longer have a 1 hour
limit.

Signed-off-by: James M Snell <jasnell@gmail.com>
Refs: nodejs#41153
Assisted-by: OpenCode
@jasnell
perf_hooks: add range options to monitorEventLoopDelay()
4fee958 
Accept `lowest`, `highest`, and `figures`, as `createHistogram()`
does. The defaults are unchanged, and use up to 432 KiB per histogram.

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
@jasnell
jasnell force-pushed the jasnell/perf-hooks-eld-range-options branch from ca68db9 to 4fee958 Compare September 25, 2026 23:35
@jasnell
jasnell requested a review from trivikr September 25, 2026 23:36
mcollina
mcollina approved these changes Sep 26, 2026
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lgtm

(linting is failing)

@panva panva added the author ready PRs with CI started, the required approvals, and no outstanding review comments. label Sep 26, 2026
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CI: https://ci.nodejs.org/job/node-test-pull-request/77956/

@panva panva added the commit-queue-rebase PRs the Commit Queue should land as multiple self-contained commits. label Sep 26, 2026
@panva panva added commit-queue PRs queued for automated landing through the Commit Queue. and removed commit-queue PRs queued for automated landing through the Commit Queue. labels Sep 26, 2026
panva
panva reviewed Sep 26, 2026
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Comment thread test/parallel/test-perf-hooks-monitor-event-loop-delay-options.js Outdated
Comment thread doc/api/perf_hooks.md Outdated
@jasnell @panva
Apply batched suggestions from code review
0e5e587 
Co-authored-by: Filip Skokan <panva.ip@gmail.com>
@jasnell jasnell added commit-queue-squash PRs the Commit Queue should land as one squashed commit. and removed commit-queue-rebase PRs the Commit Queue should land as multiple self-contained commits. labels Sep 26, 2026
@panva panva added the request-ci Add this label to start a Jenkins CI on a PR. Only starts once the PR has an approving review. label Sep 26, 2026
@github-actions github-actions Bot removed the request-ci Add this label to start a Jenkins CI on a PR. Only starts once the PR has an approving review. label Sep 26, 2026
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CI: https://ci.nodejs.org/job/node-test-pull-request/77979/

@panva panva added the resume-ci Add this label to resume the latest eligible Jenkins CI run on a PR with an approving review. label Sep 27, 2026
@github-actions github-actions Bot removed the resume-ci Add this label to resume the latest eligible Jenkins CI run on a PR with an approving review. label Sep 27, 2026
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CI: https://ci.nodejs.org/job/node-test-pull-request/77994/

@panva panva added the commit-queue PRs queued for automated landing through the Commit Queue. label Sep 27, 2026
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nodejs-github-bot merged commit 2ce7a73 into nodejs:main Sep 27, 2026
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Landed in 2ce7a73

@nodejs-github-bot nodejs-github-bot removed the commit-queue PRs queued for automated landing through the Commit Queue. label Sep 27, 2026
HoonDongKang pushed a commit to HoonDongKang/node that referenced this pull request Sep 28, 2026
@jasnell @HoonDongKang
perf_hooks: fix truncation of monitorEventLoopDelay() resolution
ce11602 
`IntervalHistogram` stored the interval as `int32_t`, so a resolution
above 2^31 - 1 ms wrapped: `resolution: 2 ** 32 + 1` sampled every
millisecond.

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
PR-URL: nodejs#66115
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
aduh95 pushed a commit that referenced this pull request Sep 28, 2026
@jasnell @aduh95
perf_hooks: fix truncation of monitorEventLoopDelay() resolution
9256a61 
`IntervalHistogram` stored the interval as `int32_t`, so a resolution
above 2^31 - 1 ms wrapped: `resolution: 2 ** 32 + 1` sampled every
millisecond.

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
PR-URL: #66115
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
aduh95 pushed a commit that referenced this pull request Sep 28, 2026
@jasnell @aduh95
perf_hooks: fix truncation of monitorEventLoopDelay() resolution
e06aa62 
`IntervalHistogram` stored the interval as `int32_t`, so a resolution
above 2^31 - 1 ms wrapped: `resolution: 2 ** 32 + 1` sampled every
millisecond.

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
PR-URL: #66115
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
@github-actions github-actions Bot mentioned this pull request Oct 5, 2026
Open
nodejs-github-bot added a commit that referenced this pull request Oct 5, 2026
@nodejs-github-bot
2026-10-07, Version 26.11.0 (Current)
7f68d75 
Notable changes:

benchmark:
  * (SEMVER-MINOR) add http header validator benchmark (James M Snell) #66334
buffer:
  * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298
  * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298
  * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064
build, doc:
  * move to redesign (Aviv Keller) #62045
http:
  * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334
http2:
  * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619
lib:
  * (SEMVER-MINOR) fix stream loading bug in node:bench (James M Snell) #66114
perf_hooks:
  * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115
  * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114
  * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099
  * (SEMVER-MINOR) report histogram memory to V8 (James M Snell) #66099
  * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099
  * (SEMVER-MINOR) add histogram export format version 2 (James M Snell) #66098
  * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098
process:
  * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213
sqlite:
  * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988
src:
  * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138
  * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737
  * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067
test:
  * deflake sliding window histogram test (James M Snell) #66132

PR-URL: #66546
aduh95 pushed a commit that referenced this pull request Oct 6, 2026
@nodejs-github-bot @aduh95
2026-10-07, Version 26.11.0 (Current)
6023800 
Notable changes:

buffer:
  * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298
  * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064
build, doc:
  * move to redesign (Aviv Keller) #62045
http:
  * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334
http2:
  * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619
perf_hooks:
  * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115
  * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114
  * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099
  * (SEMVER-MINOR) report histogram memory to V8 (James M Snell) #66099
  * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099
  * (SEMVER-MINOR) add histogram export format version 2 (James M Snell) #66098
  * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098
process:
  * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213
sqlite:
  * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988
src:
  * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138
  * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737
  * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067

PR-URL: #66546
aduh95 pushed a commit that referenced this pull request Oct 6, 2026
@nodejs-github-bot @aduh95
2026-10-07, Version 26.11.0 (Current)
49072a0 
Notable changes:

buffer:
  * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298
  * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064
build, doc:
  * move to redesign (Aviv Keller) #62045
doc:
  * promote Alpine Linux to tier 2 support (Stewart X Addison) #63737
http:
  * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334
http2:
  * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619
perf_hooks:
  * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115
  * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114
  * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099
  * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099
  * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098
process:
  * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213
sqlite:
  * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988
src:
  * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138
  * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737
  * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067

PR-URL: #66546
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@mcollina mcollina mcollina approved these changes
@panva panva panva approved these changes
@ShogunPanda ShogunPanda Awaiting requested review from ShogunPanda
@trivikr trivikr Awaiting requested review from trivikr

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@jasnell @nodejs-github-bot @mcollina @panva