test: add retry logic for eventloopdelay histogram sampling

[mcollina]

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]

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.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[nodejs-github-bot]

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

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----------------------------------- 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/
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✔ Last Jenkins CI successful
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✔ No git am in progress
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- 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

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- 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

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