1676271 - Add free-form JSON objects to capture profiling-related logging

Status: RESOLVED FIXED

(Core :: Gecko Profiler, enhancement, P3)

Description

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

It would be useful to be able to store some extra profiling-related information in the output JSON profile, so that it can at least be present in the processed profile.meta in the front-end.

For example, one thing I'd like to record is when some sub-process doesn't respond to IPCs when gathering the profile.

This will be a free-form JSON object, intended to be read by people working on the profiler, and maybe a few advanced users.
In particular it should not be considered a "stable" source of data for the front-end; no processing should happen apart from preserving it as-is in the final profile. Though we should add a way to mark identifying data so that it can be stripped on demand.

If we later consider some of its information to be useful to our users, it should be moved to another location in the profile, and the front-end could then display it in the proper manner.

At the moment I'm thinking it could be called profile.meta.profilingLog.

Comment 1

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Attachment: Bug 1676271 - Per-process profiling log - r?canaltinova

Comment 2

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Attachment: Bug 1676271 - Profile-gathering log - r?canaltinova

Depends on D150560

Comment 3

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Note: The initial bug mentioned putting the log in profile.meta, but after some prototyping I now put them at the top-level of each process, so that they can be written at the very end of generating the JSON (in case the JSON generation itself produces more logging).

The front-end processing is implemented in https://github.com/firefox-devtools/profiler/pull/4124

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8f14a0828f7b
Per-process profiling log - r=canaltinova
https://hg.mozilla.org/integration/autoland/rev/6834b438b8d6
Profile-gathering log - r=canaltinova

Comment 5

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/8f14a0828f7b
https://hg.mozilla.org/mozilla-central/rev/6834b438b8d6