November 20, 2000

By Karen Kenworthy


It's hard not to be impatient. You keep telling yourself "this won't last long," and "it will all be over soon." But then there's a delay. When will it finally be over? I guess, like all important events, it's worth the wait. I just wish they'd been more punctual.

As you probably know by now, lovely Monica (who used to keep my office in order), and her beau Bill, missed their plane from London. So their honeymoon has been extended, to include an unexpected night at the Gatwick Hilton. They'll try to catch another flight today, but it doesn't look good for the young couple. All the seats on today's flight have already been sold. :(

If you happen to see them at the hotel or the airport, tell them I said "Hi!" And tell them their Moms and Dads miss them terribly. And I do too.


I know the people of Scotland and England, who've met my Monica and Bill, will be sorry to see them go. But that's not true of everyone, or everything. Sometimes a person, or a bit of data, outstays its welcome.

I can't shed much light on the human version of this phenomena. All I know is that the lingering presence appears more often around holidays, and other times when food is in ample supply. I'm not aware of a satisfactory remedy, other than patience and endurance.

But I do know a bit about computer data that has outlived its usefulness. The data may once have been the contents of a file, now deleted. Our computer's RAM is cluttered with the residue of programs run, but now completed. Other lingering data may have been information stored in Web browser cookie, now passed its expiration date.

Whatever its origins, programmers have a colorful word for data no longer needed. They call it "garbage." Like the more familiar garbage we produce in our daily lives, this garbage tends to accumulate. But unlike normal garbage, computer garbage doesn't magically disappear from our curbs every Monday, Wednesday and Friday morning. Without some action being taken, computer garbage piles grow without limit.

Fortunately, those zany folks in the propeller-topped beanies have devised ways to deal with computer garbage. They even have a funny term for this eventual removal of useless data. They call it "garbage collection." Thanks to this process, those unwanted 0s and 1s are fully recycled, turned into useful objects such as spreadsheets, fresh Web browser cookies, and more.

Stale Cookies

Questions about computer garbage collection procedures came up recently, in some reader e-mail. Why, several people have asked, are out-of-date cookies displayed by Karen's Cookie Viewer program. Aren't expired cookies automatically deleted by my computer?

The answer is, yes, cookies past their shelf-live are automatically removed by your computer. But they aren't removed the moment they expire. Like most computer garbage, expired cookies are collected only when absolutely necessary. If the space the garbage occupies is not needed immediately, the garbage is allowed to rot. Often, it lingers for days, and even longer, waiting to be picked up and hauled away.

It may seem that computer programmers are bad housekeepers. And, of course, many are. But that's beside the point. Programmers order our computers to delay the collection of garbage for a very good reason: garbage collection takes time. And we expect our computers to use their time doing useful things, like running Power Tools, playing Solitaire, or creating resumes. We didn't buy those extra MHz so our computer could pass some sort of binary white-glove inspection.

The garbage left behind by deleted files is especially easy to collect, if you are patient. When a region of hard disk is no longer needed, your computer simply makes a note of that region's location. Later, when a new file is about to be created, or an old file grows, that region is reassigned. Only when overwritten by new data does the old data, or garbage, finally disappear.

Garbage that accumulates in RAM is handled the same way. When a program ends, the portion of RAM where it resided is put into pool of "available" RAM. But the spare RAM's contents are not cleared. Normally, the original program's image, and the data it stored, is still present in the RAM they once occupied. Later, when a new program starts, or a running program requests more RAM, the computer dips into the available RAM pool to meet the need. Finally, when a portion of RAM is reused, its original contents are replaced by new information.

Cookie recycling is done differently. Cookies, and other temporary files downloaded from the Internet, are given a quota, an amount of disk space they may occupy (you can adjust this quota via your browser's settings). As long as the total volume of these files doesn't exceed the quota, new cookies are created, and old ones are simply left lying around.

But eventually, the spaced needed to hold all existing cookies, cached images and Web pages, and other temporary Internet files, will grow to exceed even the largest quota. When that time comes, your Web browser flies into action, deleting whatever garbage it finds.

Now you might think this spate of garbage collection would leave your computer spic and span, free of garbage, storing only much needed, up-to-date files. But of course you'd be wrong. Instead, your Web browser only continues collecting garbage until it has found enough space to store the latest batch of new files and cookies. It then goes merrily on its way, doing the important job of storing and retrieving good data, and leaving the remaining garbage for another time.

Because of this just-in-time method of collecting garbage, it's quite possible for a stale cookie to linger for a long time. In fact, because cookies are small, and little space is recovered by deleting them, they are more likely to be left behind than larger files such as cached images or Web pages. Still, their time will eventually come -- either by routine garbage collection, or when a new cookie or file with the same name is downloaded.

Great Cookie Hunt

While we're talking about where cookies live, and die, I want to thank those of you who helped in last month's Great Cookie Hunt! Several hundred of you sent me excerpt from your Windows Registry, revealing the secret hiding places of the elusive web browser cookie.

This information has enabled me to create a new version of the Cookie Viewer, one which finds many more cookies when first run. Of course, like its predecessors, the new version can still search your entire hard disk for cookies if asked. But it should now find more cookies "right out of the box," including those created by other users, and by obsolete versions of Netscape and Microsoft Web browsers.

When inspecting the Windows Registry, looking for likely cookie jars, the new Cookie Viewer can now understand information recorded using the Unicode character set. It also recognizes locations that contain placeholders for such common paths (such as %SystemRoot%), and handles them appropriately.

While working on the program, I also made it easier to delete selected cookies. Now, cookies can be deleted by pressing your keyboard's <Del> key, or clicking the Delete button as before.

I even fixed a couple of bugs. One, which appeared just a couple of weeks ago, forced Microsoft Internet Explorer (MSIE) cookies to be deleted one at a time. Now, they can be deleted in big batches as before. Another young bug, now quashed, prevented you from deleting the last MSIE cookie in a particular jar. So enjoy! There's no need to let that last lonely cookie gather dust. :)

To try the new Cookie Viewer visit my Cookie Viewer home page at (Note to sharp-eyed readers: I got the link right this time <grin>). There you'll be able to download the program itself, and also its Visual Basic 6.0 source code (if you're of the programmer persuasion). As always, both are free!

That's almost all. But before we part for another week, I want to thank each of you who read this little note. This Thursday is Thanksgiving Day in my country, a day when we should consider the many blessing we've received. Your faithful support, encouragement, patience, and other kindnesses are high on my list. Thank you all.

Oh, and if you see a blithely happy young couple, waiting in the departure lounge at Gatwick, be sure to wave and say "Hi!" The honeymooners may not notice, but it's worth a try. If you see my anywhere this week, be sure to wave and say "Hi!" to me too. I'll be much less preoccupied. :)


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