1993229 - 31.74 - 2.89% Heap Unclassified / Resident Memory + 2 more (OSX, Windows) regression on Tue September 30 2025

Status: NEW

(Core :: JavaScript Engine, defect, P1)

Description

[Treeherder Bug Filer]

Perfherder has detected a awsy performance regression from push 90a55b14824b4a4856737989385a889ec0bb4902. 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)
32%	Heap Unclassified	windows11-64-24h2-shippable	fission tp6	102,707,888.16 -> 135,311,118.82
24%	Heap Unclassified	macosx1470-64-shippable	fission tp6	150,955,260.17 -> 187,479,934.28
5%	Explicit Memory	windows11-64-24h2-shippable	fission tp6	514,178,727.29 -> 538,646,198.82
3%	Resident Memory	windows11-64-24h2-shippable	fission tp6	898,649,023.76 -> 924,591,560.20

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 46987

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 1991081