1095817 - Tens of thousands of copies of specialpowers

Status: RESOLVED INCOMPLETE

(Remote Protocol :: Marionette, defect, P1)

Description

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

+++ This bug was initially created as a clone of Bug #1048833 +++

This is happening again in bug 1095714.  Somehow we have ~60000 instances of SpecialPowers in the keyboard app.

Comment 1

[Malini Das [:mdas] - Away, not checking bugmail]

I'm a bit confused, now that the bug has progressed and closes the settingslistener, does this still happen or was the special powers instance alive because the listener was alive?

Comment 2

[Malini Das [:mdas] - Away, not checking bugmail]

keep flag open so I can track this bug

Comment 3

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

The SpecialPowers stuff is in the keyboard process, while the SettingsListener stuff is in the parent process, so I doubt they're related.

Comment 4

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Any progress?

Comment 5

[Malini Das [:mdas] - Away, not checking bugmail]

It's hard to trace where this is coming from. We don't leak SP objects if we do a simple [start marionette, open app, run sp script in window, delete marionette session, kill app] cycle, but something in this process creates a bunch of additional SP objects. I don't know what makes the Keyboard app special.

In any case, we have no way to remove SpecialPowers from a window (nor remove its observers), so we can't really clean up from this. We should at least have a way to do this. If I can get a way to say 'hey, remove specialpowers and observers and all that jazz from this window object' that would help us here. Can this be added jmaher/ted?

In addition, I don't think the leak is coming from marionette, since we only add Specialpowers if it exists in that window now, and when running this test with the keyboard, I see that we only retrieve it, not create a new instance. It looks like the leak is coming from within SpecialPowers...

Comment 6

[Joel Maher ( :jmaher ) (UTC -8)]

in specialpowers we create a new instance of specialpowers for every dom window created:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowers.js#128

When we do all of this we end up doing our magic bindDOMUtils goop:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowers.js#16

which does a lot of crazy stuff:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowersAPI.js#44

Is there a way to delete the crazy stuff and the specialpowers() object?  If we could easily do that, I would be excited about seeing it in specialpowers.

Is there a chance we are accidentally creating a bunch of specialpowers() objects?  maybe we are creating a bunch of dom windows?  or is this a side effect of many tests running on the system at once?

Comment 7

[Malini Das [:mdas] - Away, not checking bugmail]

(In reply to Joel Maher (:jmaher) from comment #6)
> Is there a chance we are accidentally creating a bunch of specialpowers()
> objects?  maybe we are creating a bunch of dom windows?  or is this a side
> effect of many tests running on the system at once?

from the marionette perspective, we only create the specialpowers object if it's not attached to the current frame https://mxr.mozilla.org/mozilla-central/source/testing/marionette/marionette-listener.js?rev=27ec914bf55f#408. (aWindow is curFrame which is equal to the current content window), and I can verify that during the problematic test, we only retrieve the object, not create it...

Comment 8

[(not currently active) Ted Mielczarek]

So two things I can think of just skimming the code.
1) We do try to do some cleanup in the inner-window-destroyed observer notification:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowers.js#28

Maybe that's not firing in this case and so things are sticking around longer than they ought to?

2) By default the specialpowers script instantiates a SpecialPowersManager which listens for DOMWindowCreated events and attaches SpecialPowers to each window that gets created:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowers.js#128

You could try commenting out the line that instantiates that listener and seeing if that helps:
http://dxr.mozilla.org/mozilla-central/source/testing/specialpowers/content/specialpowers.js#138

It seems like that behavior (SpecialPowers everywhere) isn't really what you want in Marionette. If that fixes it we could tweak SP to handle your usecase better.

Comment 9

[Andrew McCreight [:mccr8]]

Nothing was fixed here, but people haven't complained about this recently, so maybe it went away.