416442 - Cycle collector debug patch

Status: RESOLVED WONTFIX

(Core :: XPCOM, defect)

Description

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Attachment: Extended logging of objects that should be freed

I used this to help me figure out why an object that I called shouldBeFreed on failed to show up in the DEBUG_CC output.

Turns out we only show objects that have external refcounts. That's great for tracking them down, but failing to say anything about the object misled jst and I for several hours.

This patch makes sure that each object that shouldBeFreed was called on shows up in the log and lists its known edges.

It also adds a '(should be garbage)' string to all the references on which shouldBeFreed was called.

Comment 1

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

So I actually would prefer not to take this -- it adds a lot of things to the output, which was previously designed to point to the objects where the problem was, so that you'd find the problem faster.

When that output was confusing me, I've generally found that I was confused because the output was more useful than I expected it to be.  There might be some ways to make it more clear (such as printing paths to multiple garbage objects, or better documentation), though.

Comment 2

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Ok, I'm not dying to have this in or anything, but I did find it useful. We can certainly WONTFIX this now that the patch lives somewhere other than my hd.

Comment 3

[Peter Van der Beken [:peterv]]

Comment on attachment 302188 [details] [diff] [review]
Extended logging of objects that should be freed

Unsetting r? until we know for sure that we want this.

Comment 4

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Oh, oops. WONTFIX.