Mozilla Cracks Down on Memory Leaks in Firefox Add-Ons

It was only a few short months ago that Mozilla put its Firefox browser on a memory “diet,” and this week it announced that it's doing much the same thing for Firefox add-ons as well.

“Leaky add-ons are a big problem,” began the blog post on Monday from Mozilla developer Nicholas Nethercote.

Accordingly, Nethercote's post outlines a summary of Mozilla's strategy to deal with such problems as well as requesting help from testers of its current Nightly versions.

'Working Splendidly'

A promising new patch, in fact, has shown great potential in addressing what Nethercote calls “chrome-to-content” leaks.

“In theory it would prevent almost all add-ons' zombie compartments, which constitute the majority of leaks from add-ons,” Nethercote explained. “And in practice, it appears to be working splendidly.”

In fact, tests of the new patch so far have found a reduction in memory consumption of as much as 400 percent, Nethercote said.

The result--regardless of hardware capabilities--can be much faster browser speeds, he added.

“Even on high-end machines with lots of RAM, leaks can greatly hurt browser performance,” Nethercote explained.

More details on the new patch can be found in a recent blog post by Kyle Huey, its creator.

The Add-On SDK

Of course, it's a rare patch that fixes any problem in one fell swoop without any side-effects, and this latest one is no exception.

To wit: At least one add-on--Wallflower, to be specific--appears to cause a new problem once the patch is applied. Turns out, however, that the glitch occurs only in add-ons built with older versions of the add-on SDK, Nethercote reported.

As a result, Mozilla asks users of the Firefox Nightly builds to file bugs if they see similar problems in any of the add-ons they use.

“Firefox 15 is scheduled for release on August 28th,” he concluded. “We need as many affected add-ons to be rebuilt with the latest SDK before that date to minimize potential problems.”

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