387005 - explain expected garbage due to unexplained reference counts better

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: patch

Currently, ExplainExpectedGarbage() is only useful on shutdown, when basically everything is expected to be garbage, since it warns about anything that is reachable from something expected to be garbage that has external references.  This patch reverses that, and makes it warn only about things from which the expected garbage can be reached.

I haven't gotten anything useful out of the patch yet, though.  That could mean there's something wrong with it, or it could mean that there are just a lot of extra references floating around in certain cases because of something key that we're failing to traverse.

Comment 1

[Graydon Hoare :graydon]

Comment on attachment 271098 [details] [diff] [review]
patch

Fine by me, whatever helps!

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Fixed.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: followup patch: include more in the graph

As a followup:  now that this is more accurate, including more in the graph always gives diagnostics that are at least as good, if not better, so we should include the roots from suspectCurrent calls when building the graph used by ExplainLiveExpectedGarbage.

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Followup checked in (with one additional comment, too).