1162679 - Decorate profile samples that go over add-on shims with add-on identifier

Status: RESOLVED INVALID

(Core :: Gecko Profiler, task, P3)

Description

[Mike Conley (:mconley) (:⚙️)]

In single-process Firefox, I believe that code running within an add-on compartment will get "decorated" in the profiler output, so it'll show the icon for the add-on alongside the samples. I could be wrong about the mechanics there, but the end result is that you can tell if some samples are the result of an add-on doing some work.

I think we're losing this information when an add-on makes use of the shims. I'm seeing profiles where there's work going on in RemoteAddonsParent and RemoteAddonsChild, and it'd be really useful if we knew which add-on was causing that activity in profiles.

Comment 1

[Markus Stange [:mstange]]

I think cleopatra does the annotation by looking at the file information for JS stack frames. I think the problem here is that sometimes the profiler doesn't see some of the JS stack frames for extension calls to RemoteAddonsParent/RemoteAddonsChild. It would be good to have a small testcase that we (or :djvj) can test with.

Comment 2

[Mike Conley (:mconley) (:⚙️)]

I wonder if we could take advantage of the fact that the addon ID is known to the shims at the point of interposition?:

https://dxr.mozilla.org/mozilla-central/source/js/xpconnect/idl/nsIAddonInterposition.idl?from=nsIAddonInterposition.idl#29

Comment 3

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

I'm not sure if this is still an issue? (With the new add-on system, Fission, etc.)
AddonInterposition doesn't seem to even exist anymore! -- These two name declarations could probably be removed.

Comment 4

[Julien Wajsberg [:julienw]]

I've seen the addon decoration regularly, so I'd say this is not happening in current browsers. But not sure!

Comment 5

[Mike Conley (:mconley) (:⚙️)]

Yeah, this bug is wayyyy invalid at this point. The add-on shims got pulled out after we switched to WebExtensions-only in 57. Nothing to do here!