1854072 - Parallel marking threshold pref not set correctly

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect, P3)

Description

[Jon Coppeard (:jonco)]

The value of the pref javascript.options.mem.gc_parallel_marking_threshold_kb is not respected if it's over 10000 (i.e. ~10MB) because there's a limit in SetMemoryPrefChangedCallbackInt:

https://searchfox.org/mozilla-central/source/dom/base/nsJSEnvironment.cpp#1942

This means that the current prefs for non-macOS platforms are not set and the default of 10MB is used instead.

Comment 1

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1847567

Comment 2

[Jon Coppeard (:jonco)]

Attachment: Bug 1854072 - Change parallel marking threshold pref to use MB instead of KB r?sfink

While the limit when setting the pref is surprising, I think it makes more
sense to change this pref to use MB like most of the other GC prefs after which
the problem will not arise.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2e9d30638c4f
Change parallel marking threshold pref to use MB instead of KB r=sfink

Comment 4

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/2e9d30638c4f

Comment 5

[BugBot [:suhaib / :marco]]

The patch landed in nightly and beta is affected.
:jonco, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox118 to wontfix.

For more information, please visit BugBot documentation.

Comment 6

[Jon Coppeard (:jonco)]

Parallel marking is disabled by default so this does not need an uplift.

Comment 7

[Jon Coppeard (:jonco)]

Attachment: Bug 1854072 - Part 2: Fix the name of the GC parameter for the parallel marking threshold r?sfink

This occurrence was missed from the previous patch and so the GC param is named
'KB' even though the value is interpreted as MB.

This affects the shell and testing functions only.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0a97f442d4da
Part 2: Fix the name of the GC parameter for the parallel marking threshold r=sfink

Comment 9

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/0a97f442d4da

Comment 10

[BugBot [:suhaib / :marco]]

Since nightly and release are affected, beta will likely be affected too.
For more information, please visit BugBot documentation.