Mozilla Updates Firefox Crash Protection

How long does a Web page need to be unresponsive before it should be considered to have crashed?

For Mozilla Firefox developers last week, the answer to that question had been ten seconds, but today, that’s no longer the case.

The open source Firefox 3.6.4 browser released last week includes a new out-of-process plugins feature that had been intended to provide crash protection for users by shutting down unresponsive processes and preventing them from crashing the entire browser.

After several days of Firefox 3.6.4’s general availability, however, it became clear to Mozilla developers however that ten seconds isn’t always enough before determining that a plugin is unresponsive.

“Following the release of Firefox 3.6.4, we heard from some users, mainly those using older computers, that they sometimes expect longer periods of non-responsiveness from plugins, especially with games,” Mike Beltzner, director of Firefox at Mozilla, wrote in a blog post. “For these users, the default timeout of?ten seconds was too short.”

As a result, the new Firefox 3.6.6 release now extends the amount of time before a page is deemed to be unresponsive from ten seconds up to 45 seconds.

In addition to users, Beltzner also thanked game vendor Zynga, developer of the popular Farmville app for Facebook, for helping Mozilla to deal with the crash protection timing issue. In the Mozilla bugzilla bug tracking system, developer Justin Dolske reported on June 25 that Farmville in particular had issues with Firefox 3.6.4.

“I do understand that there’s a massive regression in user experience for a meaningful number of users of an extremely popular property, and that a raised timeout remedies it,” Mike Shaver, vice president of engineering at Mozilla, noted in the same bugzilla thread.

The ten-second crashing issue had not come to light prior to the Firefox 3.6.4 release, despite a large number of users testing development builds of Firefox 3.6.4 for over a month. During the Firefox 3.6.4 development and beta release cycle, Beltzner noted that nearly one million users tested the browser before it was officially released. The first public beta for Firefox 3.6.4 came out at the end of April.

Sean Michael Kerner is a senior editor at, the news service of, the network for technology professionals.

Sean Michael Kerner
Sean Michael Kerner
Sean Michael Kerner is an Internet consultant, strategist, and contributor to several leading IT business web sites.

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