Firefox: On leaky memory and bumping blockers

Computerworld - Although Firefox 3.0 leaks less memory than its predecessor, Mozilla Corp.'s lead engineer today wouldn't promise that every last hole has been plugged.

Talking the day after the company released the first beta of Firefox 3.0, Mozilla's vice president of engineering, Mike Schroepfer, called the browser's problems "quite complicated" but said he was confident that users will see significant improvements in how it handles memory.

"There are a number of different memory issues, including when Firefox doesn't return allocated memory to the system," Schroepfer said, referring to the classic leak that's driven Firefox's reputation as a memory hog. Over the years, users have complained that the longer Firefox is left running, the more memory it consumes; ultimately, it grabs enough to slow down the host computer.

Just last week, in fact, a Mozilla Corp. board member pinned any possibility of competing in the mobile space with Opera Software ASA on solving Firefox's memory issues. Opera Mini is the leading cell phone browser.

"We've been hunting memory leaks for about three years now," said Schroepfer, "and we fixed 50 to 60 in Firefox 2.0. But we took a much harder spin through [the problem] for 3.0 and fixed more than 300 individual leaks. I think [3.0] will be better than 2.0, which was better than 1.5. Compared to earlier versions, and compared to other browsers, users will see significant improvements."

But while he claimed that Mozilla has made major strides in memory management, Schroepfer argued that the company doesn't have complete control over Firefox's appetite. "The Web changes, applications change. We've gone from static pages to full applications, Office-like applications. We're doing a lot more with the browser, and we're opening lots of tabs and keeping lots of windows open at once." All that activity, he said, means the browser uses more memory.

But now, with Firefox 3.0 entering the next stage of testing, Schroepfer's attention is less on what's been done than on what needs to wrap up to get the browser out the door. Not that that will happen tomorrow. "We're going to do at least three betas, with Beta 2 by the end of the year and Beta 3 at the beginning of next year. After that, we'll evaluate and see where we are."

He refused to set a deadline for a final version, or even a timetable for the release candidates that Mozilla typically runs through prior to declaring a browser ready. "We want to finish it up, of course, but with the quality that's expected of Mozilla. We have to do the right thing," he said.