{"id":2020,"date":"2012-07-19T11:46:01","date_gmt":"2012-07-19T00:46:01","guid":{"rendered":"http:\/\/blog.mozilla.org\/nnethercote\/?p=2020"},"modified":"2012-07-19T14:39:42","modified_gmt":"2012-07-19T03:39:42","slug":"firefox-15-plugs-the-add-on-leaks","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/nnethercote\/2012\/07\/19\/firefox-15-plugs-the-add-on-leaks\/","title":{"rendered":"Firefox 15 plugs the add-on leaks"},"content":{"rendered":"

TL;DR<\/h3>\n

Firefox 15 prevents most memory leaks caused by add-ons, including Firebug.\u00a0 For many users with add-ons installed this will significantly reduce Firefox’s memory consumption, without requiring upgrades to those add-ons.<\/p>\n

For those users, Firefox 15 is likely to be faster (sometimes drastically so) and less likely to crash, especially if they have multiple add-ons installed and\/or keep Firefox running for a long time between restarts.<\/p>\n

The Problem<\/h3>\n

A memory leak<\/em><\/a> occurs when a program allocates some memory but then fails to free it.\u00a0 There are multiple causes of memory leaks, but they all have the same effect:\u00a0 an increase in memory consumption, which often grows as the program runs. This can cause poor performance, and even lead to crashes or aborts due to the exhaustion of available memory.<\/p>\n

Many Add-ons Leak<\/h4>\n

I’ve lost count of the number of times I’ve seen (and participated in) variants of the following conversation during the past year.<\/p>\n

Alice: Firefox is slow and using 2GB of memory.  WTF?\r\nBob:\u00a0  Do you have any add-ons installed?\r\nAlice: Yes.  Why?\r\nBob:\u00a0  Try disabling them all and restart Firefox.\r\nAlice: Ok... Oh wow.  That's much better.\r\nBob:\u00a0  Now you have to disable them one at a time to work\r\n       <\/em>out which one(s) are at fault.\r\nAlice: Really?  Hmm, that sucks.\r\nBob:\u00a0  Yeah.  Sorry about that.<\/pre>\n
Although Firefox itself isn’t immune to memory consumption problems, Mozilla’s MemShrink project<\/a> has fixed enough problems<\/a> in Firefox itself that in January of this year I declared that the #1 way to improve memory consumption in Firefox would be with “Better Detection and Notification of Leaky Add-ons<\/a>“.<\/p>\n
I said this because many add-ons have memory leaks<\/a>.<\/p>\n