936292 - Somehow track large ArrayBuffers on a per-zone or -compartment basis

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Andrew McCreight [:mccr8]]

For bug 936128 and bug 936218 we want to be able to quickly tell if a compartment (or maybe zone?) has any large array buffers.  For the former, we may also want to be able to get those buffers immediately, though it may be okay to just look at everything in the compartment to find them.

The minimum implementation here would have a counter of large buffers that would be increased when one is allocated and decreased when one is freed.  A more complex thing would have some kind of weak map of them.

It should be configurable via a pref what it means for an array buffer to be large.  On a phone, 10mb may be large, where on desktop 100mb may be better.

Note that configurability can interact with the implementation of the tracking. If we have a limit of 100mb, create a 150mb buffer, then increase the limit to 200mb, we have to make sure that our counter doesn't get messed up (the 150mb buffer will no longer count as "big" when removed), or remove them from the weak map or something.

Comment 1

[Andrew McCreight [:mccr8]]

Luke went with some other approach for dealing with large array buffers that doesn't need this.