I wrote last week about leaky add-ons. Specifically, Kyle Huey landed a patch that in most cases prevents zombie compartments, which are the most common kind of memory leak in add-ons. However, this change itself caused a different memory leak in some add-ons built with versions 1.3 and earlier of the Add-on SDK. I described this as “two steps forward, one step back”.

Happily, Kyle landed a patch that slightly delayed the cutting of the chrome-to-content references. This has the following consequences.

It doesn’t compromise the “two steps forward”.

It fixes the “one step back”.

It should reduce the potential for similar, as-yet-unknown backward steps.

The repacking of add-ons with newer versions of the Add-on SDK is now less urgent than it was. It’s still a good idea, though, because older version had some other, albeit much smaller, leaks.

This is good news. Firefox 15 is scheduled for release on August 28. Assuming we don’t hit other problems with these changes prior to release, for users with add-ons there’s a good chance that Firefox 15 will use less memory and suffer fewer annoying pauses.

Once again, it would be great if users of Nightly builds, particularly those that use add-ons, could pay attention to memory consumption and file bugs for any bad behaviour. Thanks!