1422264 - Most non-incremental GCs are reported as being due to failed gray buffering

Status: RESOLVED FIXED

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

Description

[Jon Coppeard (:jonco)]

In bug 1420333 we added a non-incremental reason to report when gray buffering failed.  However since we don't buffer gray roots for non-incremental GCs this makes almost all non-incremental GCs report as being due to failed gray buffering.

See telemetry alert: http://alerts.telemetry.mozilla.org/index.html#/detectors/1/metrics/2042/alerts/?from=2017-11-27&to=2017-11-27

Comment 1

[Paul Bone [:pbone]]

Attachment: Bug 1422264 - Don't switch to non-incremental GC mode if it's already non-incremental

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/fa3851e29821
Don't switch to non-incremental GC mode if it's already non-incremental r=sfink

Comment 3

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/fa3851e29821

Comment 4

[Paul Bone [:pbone]]

Hi Jon,

How can we verify that the telemetry alart has gone away?  I guess we now have to wait a couple of days anyway.

Cheers.

Comment 5

[Jon Coppeard (:jonco)]

Yes, in a few days I will hopefully get another alert saying that this has gone back to the original state.

Comment 6

[Jon Coppeard (:jonco)]

(In reply to Jon Coppeard (:jonco) from comment #5)
In the meantime we can watch the telemetry for GC_NON_INCREMENTAL_REASON:

https://telemetry.mozilla.org/new-pipeline/evo.html#!aggregates=bucket-0!bucket-1!bucket-2!bucket-3!bucket-4!bucket-5!bucket-6!bucket-7!bucket-8!bucket-9!bucket-10!bucket-11!bucket-12!bucket-13!bucket-14!bucket-15!bucket-16!bucket-17!bucket-18!bucket-19!bucket-20&cumulative=0&end_date=null&keys=&max_channel_version=nightly%252F59&measure=GC_NON_INCREMENTAL_REASON&min_channel_version=nightly%252F59&processType=*&product=Firefox&sanitize=1&sort_keys=submissions&start_date=null&trim=1&use_submission_date=0

Comment 7

[Paul Bone [:pbone]]

Telemetry seems to have returned to normal.