2001100 - 8.56 - 7.2% damp jstracer.profiler-recording-performance.DAMP / damp jstracer.profiler-recording-performance.DAMP + 1 more (Linux, OSX, Windows) regression on Thu November 13 2025

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a devtools performance regression from push 13d65a94e4cf6a7bb3ec9c239156a090d0884619. As author of one of the patches included in that push, we need your help to address this regression.

Please acknowledge, and begin investigating this alert within 3 business days, or the patch(es) may be backed out in accordance with our regression policy. Our guide to handling regression bugs has information about how you can proceed with this investigation.

If you have any questions or need any help with the investigation, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Regressions:

Ratio	Test	Platform	Options	Absolute values (old vs new)
9%	damp jstracer.profiler-recording-performance.DAMP	macosx1470-64-shippable	e10s fission stylo webrender	313.73 -> 340.59
8%	damp jstracer.profiler-recording-performance.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	140.34 -> 151.29
7%	damp jstracer.profiler-recording-performance.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	533.56 -> 571.98

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
5%	damp custom.jsdebugger.stepIn.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	2,983.99 -> 2,838.34
4%	damp custom.jsdebugger.stepInNewSource.big-bundle.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	2,330.33 -> 2,228.39
4%	damp custom.jsdebugger.stepInNewSource.big-bundle.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	984.58 -> 946.03
4%	damp custom.jsdebugger.stepInNewSource.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	864.85 -> 833.34
4%	damp custom.jsdebugger.stepIn.big-bundle.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	3,162.21 -> 3,048.39
...	...	...	...	...
3%	damp custom.jsdebugger.stepIn.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	1,306.43 -> 1,273.30

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask [e-mail] to do that for you.

You can run all of these tests on try with ./mach try perf --alert 47456

The following documentation link provides more information about this command.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1997192

Comment 2

[Matthew Gaudet (he/him) [:mgaudet]]

This will be resolved by backout.

Comment 3

[Ryan VanderMeulen [:RyanVM]]

Fixed by backout.