test: add retry logic for eventloopdelay histogram sampling by mcollina · Pull Request #61796 · nodejs/node · GitHub

Summary

Fixes flaky test-performance-eventloopdelay test on sharedlibs builds.

Problem

On some build configurations (e.g., Ubuntu 24.04 sharedlibs), the histogram may not record valid samples (min > 0) after the initial spinning period. The test fails with:

AssertionError [ERR_ASSERTION]: assert(histogram.min > 0)

The previous fix (PR #61629) added setImmediate to allow samples to be recorded, but this wasn't sufficient for all configurations.

Solution

Add a retry mechanism that checks if valid samples have been recorded (count > 0 && min > 0 && max > 0). If not, the test will spin the event loop additional times (up to 3 retries) before asserting.

This ensures the test passes on slower or differently-configured systems where event loop delay sampling may take longer to produce measurable results.

Verification

Tested locally with python3 tools/test.py --repeat 30 - all passed.

Refs: nodejs/reliability#1461

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.71%. Comparing base (4a13a62) to head (64c291a).
⚠️ Report is 903 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61796      +/-   ##
==========================================
- Coverage   89.76%   89.71%   -0.05%     
==========================================
  Files         675      675              
  Lines      204674   204797     +123     
  Branches    39330    39348      +18     
==========================================
+ Hits       183716   183734      +18     
- Misses      13235    13336     +101     
- Partials     7723     7727       +4

see 52 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
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On some build configurations (e.g., sharedlibs), the histogram may not record valid samples (min > 0) after the initial spinning period. This adds a retry mechanism that will spin the event loop additional times if valid samples haven't been recorded yet. This helps ensure the test passes on slower or differently-configured systems where event loop delay sampling may take longer to produce measurable results. Refs: nodejs/reliability#1461

Extract assertions into separate function and simplify control flow. Use setImmediate for final assertions to ensure histogram has recorded all samples.

CI: https://ci.nodejs.org/job/node-test-pull-request/73370/

Commit Queue failed

- Loading data for nodejs/node/pull/61796 ✔ Done loading data for nodejs/node/pull/61796 ----------------------------------- PR info ------------------------------------ Title test: add retry logic for eventloopdelay histogram sampling (#61796) Author Matteo Collina <matteo.collina@gmail.com> (@mcollina) Branch mcollina:fix-flaky-test-performance-eventloopdelay-v2 -> nodejs:main Labels test Commits 2 - test: add retry logic for eventloopdelay histogram sampling - test: refactor eventloopdelay test for clarity Committers 1 - Matteo Collina <hello@matteocollina.com> PR-URL: https://github.com/nodejs/node/pull/61796 Refs: https://github.com/nodejs/reliability/issues/1461 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/61796 Refs: https://github.com/nodejs/reliability/issues/1461 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com> -------------------------------------------------------------------------------- ℹ This PR was created on Thu, 12 Feb 2026 22:07:51 GMT ✔ Approvals: 4 ✔ - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-3797902216 ✔ - Colin Ihrig (@cjihrig): https://github.com/nodejs/node/pull/61796#pullrequestreview-3797906488 ✔ - Paolo Insogna (@ShogunPanda) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-4261607012 ✔ - Richard Lau (@richardlau) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-4263460373 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2026-05-11T12:08:59Z: https://ci.nodejs.org/job/node-test-pull-request/73370/ - Querying data for job/node-test-pull-request/73370/ ✔ 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 61796 From https://github.com/nodejs/node * branch refs/pull/61796/merge -> FETCH_HEAD ✔ Fetched commits as 0a60e9013bb9..64c291afb908 -------------------------------------------------------------------------------- [main 9caf8f098e] test: add retry logic for eventloopdelay histogram sampling Author: Matteo Collina <hello@matteocollina.com> Date: Thu Feb 12 23:07:10 2026 +0100 1 file changed, 62 insertions(+), 45 deletions(-) [main 5d9d4fb500] test: refactor eventloopdelay test for clarity Author: Matteo Collina <hello@matteocollina.com> Date: Sat Feb 14 17:47:16 2026 +0100 1 file changed, 48 insertions(+), 45 deletions(-) ✔ Patches applied There are 2 commits in the PR. Attempting autorebase. (node:396) [DEP0190] DeprecationWarning: Passing args to a child process with shell option true can lead to security vulnerabilities, as the arguments are not escaped, only concatenated. (Use `node --trace-deprecation ...` to show where the warning was created) Rebasing (2/4)

�[KExecuting: git node land --amend --yes
⚠ Found Refs: https://github.com/nodejs/reliability/issues/1461, skipping..
--------------------------------- New Message ----------------------------------
test: add retry logic for eventloopdelay histogram sampling

On some build configurations (e.g., sharedlibs), the histogram may not
record valid samples (min > 0) after the initial spinning period. This
adds a retry mechanism that will spin the event loop additional times
if valid samples haven't been recorded yet.

This helps ensure the test passes on slower or differently-configured
systems where event loop delay sampling may take longer to produce
measurable results.

Refs: nodejs/reliability#1461
PR-URL: #61796
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

[detached HEAD e60a0ec86a] test: add retry logic for eventloopdelay histogram sampling
Author: Matteo Collina <hello@matteocollina.com>
Date: Thu Feb 12 23:07:10 2026 +0100
1 file changed, 62 insertions(+), 45 deletions(-)
Rebasing (3/4)
Rebasing (4/4)

�[KExecuting: git node land --amend --yes
--------------------------------- New Message ----------------------------------
test: refactor eventloopdelay test for clarity

Extract assertions into separate function and simplify control flow.
Use setImmediate for final assertions to ensure histogram has
recorded all samples.

PR-URL: #61796
Refs: nodejs/reliability#1461
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

[detached HEAD f8d7aba6d5] test: refactor eventloopdelay test for clarity
Author: Matteo Collina <hello@matteocollina.com>
Date: Sat Feb 14 17:47:16 2026 +0100
1 file changed, 48 insertions(+), 45 deletions(-)

�[KSuccessfully rebased and updated refs/heads/main.

ℹ Add commit-queue-squash label to land the PR as one commit, or commit-queue-rebase to land as separate commits.

https://github.com/nodejs/node/actions/runs/25685898940

Commit Queue failed

- Loading data for nodejs/node/pull/61796 ✔ Done loading data for nodejs/node/pull/61796 ----------------------------------- PR info ------------------------------------ Title test: add retry logic for eventloopdelay histogram sampling (#61796) Author Matteo Collina <matteo.collina@gmail.com> (@mcollina) Branch mcollina:fix-flaky-test-performance-eventloopdelay-v2 -> nodejs:main Labels test, commit-queue-squash Commits 2 - test: add retry logic for eventloopdelay histogram sampling - test: refactor eventloopdelay test for clarity Committers 1 - Matteo Collina <hello@matteocollina.com> PR-URL: https://github.com/nodejs/node/pull/61796 Refs: https://github.com/nodejs/reliability/issues/1461 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/61796 Refs: https://github.com/nodejs/reliability/issues/1461 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com> -------------------------------------------------------------------------------- ℹ This PR was created on Thu, 12 Feb 2026 22:07:51 GMT ✔ Approvals: 4 ✔ - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-3797902216 ✔ - Colin Ihrig (@cjihrig): https://github.com/nodejs/node/pull/61796#pullrequestreview-3797906488 ✔ - Paolo Insogna (@ShogunPanda) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-4261607012 ✔ - Richard Lau (@richardlau) (TSC): https://github.com/nodejs/node/pull/61796#pullrequestreview-4263460373 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2026-05-11T17:29:59Z: https://ci.nodejs.org/job/node-test-pull-request/73370/ - Querying data for job/node-test-pull-request/73370/ ✔ 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 61796 From https://github.com/nodejs/node * branch refs/pull/61796/merge -> FETCH_HEAD ✔ Fetched commits as 0a60e9013bb9..64c291afb908 -------------------------------------------------------------------------------- [main 36fc919cb8] test: add retry logic for eventloopdelay histogram sampling Author: Matteo Collina <hello@matteocollina.com> Date: Thu Feb 12 23:07:10 2026 +0100 1 file changed, 62 insertions(+), 45 deletions(-) [main cca689e6e5] test: refactor eventloopdelay test for clarity Author: Matteo Collina <hello@matteocollina.com> Date: Sat Feb 14 17:47:16 2026 +0100 1 file changed, 48 insertions(+), 45 deletions(-) ✔ Patches applied There are 2 commits in the PR. Attempting to fixup everything into first commit. [main fb48362ff4] test: add retry logic for eventloopdelay histogram sampling Author: Matteo Collina <hello@matteocollina.com> Date: Thu Feb 12 23:07:10 2026 +0100 1 file changed, 66 insertions(+), 46 deletions(-) ⚠ Found Refs: https://github.com/nodejs/reliability/issues/1461, skipping.. --------------------------------- New Message ---------------------------------- test: add retry logic for eventloopdelay histogram sampling

On some build configurations (e.g., sharedlibs), the histogram may not
record valid samples (min > 0) after the initial spinning period. This
adds a retry mechanism that will spin the event loop additional times
if valid samples haven't been recorded yet.

This helps ensure the test passes on slower or differently-configured
systems where event loop delay sampling may take longer to produce
measurable results.

Refs: nodejs/reliability#1461
PR-URL: #61796
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

[main 59528f1c9f] test: add retry logic for eventloopdelay histogram sampling
Author: Matteo Collina <hello@matteocollina.com>
Date: Thu Feb 12 23:07:10 2026 +0100
1 file changed, 66 insertions(+), 46 deletions(-)
✖ 59528f1c9fde8b832bf42dc30de1b13fdc833dcc
✔ 0:0 no Assisted-by metadata assisted-by-is-trailer
✔ 0:0 no Co-authored-by metadata co-authored-by-is-trailer
✔ 0:0 skipping fixes-url fixes-url
✔ 0:0 blank line after title line-after-title
✔ 0:0 line-lengths are valid line-length
✔ 0:0 metadata is at end of message metadata-end
✔ 11:8 PR-URL is valid. pr-url
✔ 0:0 reviewers are valid reviewers
✖ 0:0 Commit must have a "Signed-off-by" trailer signed-off-by
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✔ 0:0 Title is formatted correctly. title-format
⚠ 0:50 Title should be <= 50 columns. title-length

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nodejs-github-bot added needs-ci PRs that need a full CI run. test Issues and PRs related to the tests. labels Feb 12, 2026

mcollina force-pushed the fix-flaky-test-performance-eventloopdelay-v2 branch 2 times, most recently from a0b9aa0 to ad1c0a7 Compare February 13, 2026 10:43

jasnell approved these changes Feb 13, 2026

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test: refactor eventloopdelay test for clarity

64c291a

Extract assertions into separate function and simplify control flow. Use setImmediate for final assertions to ensure histogram has recorded all samples.

mcollina force-pushed the fix-flaky-test-performance-eventloopdelay-v2 branch from ad1c0a7 to 64c291a Compare February 14, 2026 16:48

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mcollina reopened this May 28, 2026

mcollina closed this May 28, 2026

test: add retry logic for eventloopdelay histogram sampling by mcollina · Pull Request #61796 · nodejs/node · GitHub

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test: add retry logic for eventloopdelay histogram sampling - #61796

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test: add retry logic for eventloopdelay histogram sampling by mcollina · Pull Request #61796 · nodejs/node · GitHub

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Refs: nodejs/reliability#1461 PR-URL: #61796 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com>

PR-URL: #61796 Refs: nodejs/reliability#1461 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com>

�[KSuccessfully rebased and updated refs/heads/main.

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Refs: nodejs/reliability#1461 PR-URL: #61796 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Richard Lau <richard.lau@ibm.com>

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test: add retry logic for eventloopdelay histogram sampling#61796
mcollina wants to merge 2 commits into
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mcollina:fix-flaky-test-performance-eventloopdelay-v2

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Refs: nodejs/reliability#1461
PR-URL: #61796
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

PR-URL: #61796
Refs: nodejs/reliability#1461
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

Refs: nodejs/reliability#1461
PR-URL: #61796
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Richard Lau <richard.lau@ibm.com>