1298346 - Investigate overrunning sweep slices to ensure we make progress

Status: NEW

(Core :: JavaScript: GC, defect, P3)

Description

[Jon Coppeard (:jonco)]

One thing that came up while looking into bug 1293127 is that we sometimes spend many slices sweeping without seeming to make progress.  This could be because we never finish doing the barrier marking before we exhaust our slice budget and so never get to sweep anything.

We should investigate adding some kind of heuristic to get round this.  For example we could set a minimum amount of sweeping to do even if it means overrunning the budget.  Or if we don't start sweeping after N slices, we could start increasing the budget by a certain factor.