1487198 - Consider memory-reporting more things on DocumentOrShadowRoot

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Boris Zbarsky [:bzbarsky]]

With the memory reporting DocumentOrShadowRoot does after bug 1486623, we should consider moving more things into DocumentOrShadowRoot::SizeOfExcludingThis.

As a specific example, nsDocument::DocAddSizeOfExcludingThis has:

  aWindowSizes.mDOMOtherSize +=
    mIdentifierMap.SizeOfExcludingThis(aWindowSizes.mState.mMallocSizeOf);

and we should move that up into DocumentOrShadowRoot.  I am looking at a DMD log shows this (due to elements with ids in an <svg:use> subtree):

Unreported {
  2,201 blocks in heap block record 11 of 6,988
  2,253,824 bytes (1,408,640 requested / 845,184 slop)
  Individual block sizes: 1,024 x 2,201
  0.47% of the heap (20.64% cumulative)
  1.27% of unreported (56.08% cumulative)
  Allocated at {
    #01: replace_calloc(unsigned long, unsigned long) (DMD.cpp:1282, in libmozglue.dylib)
    #02: PLDHashTable::Add(void const*, std::nothrow_t const&) (PLDHashTable.h:245, in XUL)
    #03: PLDHashTable::Add(void const*) (PLDHashTable.cpp:619, in XUL)
    #04: mozilla::dom::ShadowRoot::AddToIdTable(mozilla::dom::Element*, nsAtom*) (nsTHashtable.h:156, in XUL)
    #05: mozilla::dom::Element::BindToTree(nsIDocument*, nsIContent*, nsIContent*) (Element.cpp:0, in XUL)
    #06: nsSVGElement::BindToTree(nsIDocument*, nsIContent*, nsIContent*) (nsSVGElement.cpp:240, in XUL)
    #07: nsINode::InsertChildBefore(nsIContent*, nsIContent*, bool) (nsINode.cpp:1412, in XUL)
    #08: mozilla::dom::SVGUseElement::UpdateShadowTree() (RefPtr.h:42, in XUL)
  }
}

Of course it's worth figuring out whether this hashtable ever gets used in the <svg:use> case...

Comment 1

[Boris Zbarsky [:bzbarsky]]

I guess mDOMStyleSheets is the only other thing on DocumentOrShadowRoot that might need memory reporting...

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Yeah, can get to this tomorrow.

The identifier map is actually used, it's needed to efficiently lookup idrefs in Shadow DOM subtrees... Though for <svg:use> we jump over them so we could potentially avoid doing it.

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Given it doesn't have it in document, I'll just move the identifier map for now.

Comment 4

[Emilio Cobos Álvarez [:emilio]]

Attachment: Measure memory usage of the identifier map in ShadowRoot as well.

Comment 5

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

Comment on attachment 9005060 [details]
Measure memory usage of the identifier map in ShadowRoot as well.

Olli Pettay [:smaug] has approved the revision.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/48f88e237b4e
Measure memory usage of the identifier map in ShadowRoot as well. r=smaug

Comment 7

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/48f88e237b4e