423723 - GMail leaks multiple windows and documents

Status: RESOLVED INVALID

(Core :: DOM: Core & HTML, defect, P2)

Description

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

Logging in to GMail I see a *ton* of cycle collector warnings. We've definitely got some unknown references that hold windows alive. Trying to narrow it down means making the docshell a CC participant, at least for debugging purposes.

Comment 1

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

If gmail leaks just sitting around we should really try to fix that.

Comment 2

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Ben, what's the latest here?

Comment 3

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

After a lot of toil this bug is INVALID.

As dbaron pointed out our CC 'hints' that certain objects should be collectable are only best guesses and are not 100% accurate. Basically what I believe is happening here is that gmail is holding on to windows after they are closed. As soon as the window is closed we tell the CC that the window should be garbage, which is not true, and the CC spits out tons of warnings.

Similar CC output can be seen using attachment 311639 [details] in bug 424449.

Sadly there really wasn't a good way to tell all this from the original output, I had to make the docshell main-thread-only by freshening the patch in bug 243591 and then add it to CC in bug 372107.

We're also going to have to figure out what to do about XMLHttpRequest in the future... It's a CC participant that is currently tied up in reference cycles with necko channels and callbacks, and the CC complains about necko's ownership.

Comment 4

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

Oh, crap, forgot to say that fixing bug 424451 is the best way I know of to avoid this false-positive warning.