Internet & Technology

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You are using a cache right now.  So what is it and why should I care?

Definition of a Cache

In computer science, a cache is a component that improves performance by transparently storing data such that future requests for that data can be served faster. 

Most modern computers have a high speed instructional cache that fetches and executes streams of instructions without using slower speed methods that depend upon slower memory.

The cache we are most concerned with is the browser cache.  As  you go browsing, you will traverse an number of  pages that you can go back and look at via the back button on any of the popular browsers.  The browser gives them higher speed because they just grab the page that you looked at seconds, minutes or hours ago from your computer's memory without having to go out on the net and fetch it again.

Many of these pages do not refresh themselves when you go get them.  So if you are interested in the latest page, you should click F5 on your keyboard.  On the MAC you can use the Apple Key + R.  Some of the browsers are not happy to refresh some pages especially in frames.  You have to make sure your cursor is in the area of the screen you want to refresh.  Even then, some, like Chrome and Safari don't work properly.

Why is the Cache important?

You need the latest information, so make sure you refresh, if in doubt.  Of course some reference material does not change so refreshing is a waste of time..  Whatever is on the page could have been changed, however, since  your last visit.  Many web sites that change all the time try to refresh the current page on a reasonable time frame for all viewers  The standard methods for doing this work well on Internet Explorer and Firefox, but are quirky on Chrome and Apple's Safari, where bugs exist.

Many web programmers force a refresh by going around the browser and doing it from the server side and not waiting for the client (your browser) to get around to do it

Good examples of this are both Gmail and Hot Mail.  You'd not like it if your latest email message has not shown up as required and you were forced to click a button or combination of keys in the case of the MAC.  Of course all these browsers have a pull-down menu to do a refresh too, but a single key is faster.  Both can be quirky

Many web sites just don't refresh and if you don't force them to do so, you'll be seeing old information on some pages until you clear the cache or reboot or both.  So pay attention to your cache. Some browsers allow you to eliminate the cache altogether, but this will slow down normal browsing.

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Thursday, April 21, 2011