Firefox 15 is a week out the door now and one of the biggest additions has been a patch that should fix most memory leaks caused by add-ons. The change affects zombie compartments, memory kept in use by these add-ons even after the page that needed it is closed.
In one move, old bugs with well-known add-ons which had been causing problems for a long time, Firebug for example, were solved.
Such a big change can cause problems though, especially with so many add-ons out there. In fact, one issue was discovered very quickly, the patch actually caused Greasemonkey scripts to leak badly
. The issue was quickly fixed.
At the moment, Mozilla is aware of a couple of add-ons which still have leaks, Scriptish, a Greasemonkey fork, and Speed Dial.
The patch also affected some add-ons, the aforementioned Greasemonkey, AutoPager and TabMixPlus, Mozilla's Nicholas Nethercote who's been leading the MemShrink project, listed.
Overall though, it looks like the transition to Firefox 15 with the add-on leak patch
has been very smooth. What's more, it also means that users will be getting a much lighter and snappier browser. Combined with other MemShrink efforts as well as upcoming improvements, Firefox should get slimmer and slimmer.
It's already a contender for the slimmest desktop browser, something inconceivable even a year ago. Granted, the other browsers, Chrome in particular, have been getting "fatter" recently.
That said, if you do encounter problems with your add-ons because of the Firefox 15 patch, make yourself heard, Firefox devs love feedback.
"If you have any additional add-ons that you think have been adversely affected by Firefox 15, open the error console and use the 'filter' search box in the top right-hand corner to look for a message that says 'TypeError: can’t access dead object' — that’s the message that indicates an add-on is trying to access memory via a reference that Firefox 15 has pre-emptively cut. Please report any problems in Bugzilla and put '[MemShrink]' in the whiteboard field," Nethercote wrote