735550 - unmark gray objects held alive by nsXBLDocGlobalObject of skippable nsXBLDocumentInfo

Status: RESOLVED FIXED

(Core :: XBL, defect)

Description

[Andrew McCreight [:mccr8]]

This is another pattern that shows up very frequently on my simple test case of Gmail + error console: there's an nsXBLDocumentInfo that appears to be live, but it contains an nsXBLDocGlobalObject that points to a JSContext that points to another JSContext, which points to an "nsXBLPrototypeScript compilation scope" object, that reaches about 45 JS objects.  I think we can extend the CanSkip function for nsXBLDocumentInfo to reach through that chain and unmarkGray what the JSContext holds onto.  I see about a dozen of these in my CC graph, so that could be another 540 nodes we could get rid of.

Comment 1

[Andrew McCreight [:mccr8]]

I should probably also just make nsXBLDocumentInfo into a skippable class, as there are a dozen or so in the graph with no children.

Comment 2

[Andrew McCreight [:mccr8]]

Attachment: WIP

Comment 3

[Andrew McCreight [:mccr8]]

I just piggybacked on nsXBLDocumentInfo::MarkInCCGeneration instead of turning nsXBLDocumentInfo into a skippable class. I think we should use a more general solution for childless nodes.

Comment 4

[Andrew McCreight [:mccr8]]

Attachment: mark global held by live XBLDocInfo

Comment 5

[Andrew McCreight [:mccr8]]

Comment on attachment 606787 [details] [diff] [review]
mark global held by live XBLDocInfo

This had a good try run with some of my other patches.
https://tbpl.mozilla.org/?tree=Try&rev=869ed959b506

In the medium term, I want to move all of these two unmarking functions that MarkInCCGeneration (unmark protos and unmark script context) into the GC.  If you think it makes sense, Olli, I can just directly do that instead of having this intermediate bug.

Comment 6

[Olli Pettay [:smaug][[e-mail]]]

Comment on attachment 606787 [details] [diff] [review]
mark global held by live XBLDocInfo

We could do this now.

Comment 7

[Andrew McCreight [:mccr8]]

Thanks for the reviews.

https://hg.mozilla.org/integration/mozilla-inbound/rev/7c0ac8201f4e

Comment 8

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

https://hg.mozilla.org/mozilla-central/rev/7c0ac8201f4e