Add-ons are causing significantly fewer leaks than before

Sep 5, 2012 12:40 GMT  ·  By

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.