Editor’s Note: Today marks a special day for WordPress. Powering many websites (and yes, Smashing Magazine is one of them), it celebrates its 13th birthday today. Happy birthday, dear WordPress! Here’s to many more!
Do you remember when you could run a “fast” WordPress website with just an Apache server and PHP? Yeah, those were the days! Things were a lot less complicated back then.
Now, everything has to load lightning-fast! Visitors don’t have the same expectations about loading times as they used to. A slow website can have serious implications for you or your client.
Varnish Cache is an open source HTTP accelerator that is used for speeding up the content delivery of the world’s top content-heavy dynamic websites. However, the performance or speed a newcomer to Varnish Cache can expect from its deployment can be quite nebulous.
This is true for users at both extremes of the spectrum: from those who play with its source code to create more complex features to those who set up Varnish Cache using the default settings.
The web is moving toward using HTTPS encryption by default. This move has been encouraged by Google, which announced that HTTPS would be a ranking signal. However, moving your website to HTTPS is good for other reasons, too.
Rather than debate those reasons, this article assumes you have already decided to move to HTTPS. We’ll walk through how to move your website to HTTPS, taking advantage of Varnish Cache.
Phil Karlton once said, “There are only two hard things in Computer Science: cache invalidation and naming things.” This article is about the harder of these two: cache invalidation. It’s directed at readers who already work with Varnish Cache. To learn more about it, you’ll find background information in “Speed Up Your Mobile Website With Varnish.”
10 microseconds (or 250 milliseconds): That’s the difference between delivering a cache hit and delivering a cache miss. How often you get the latter will depend on the efficiency of the cache — this is known as the “hit rate.” A cache miss depends on two factors: the volume of traffic and the average time to live (TTL), which is a number indicating how long the cache is allowed to keep an object. As system administrators and developers, we can’t do much about the traffic, but we can influence the TTL.
Imagine that you have just written a post on your blog, tweeted about it and watched it get retweeted by some popular Twitter users, sending hundreds of people to your blog at once. Your excitement at seeing so many visitors talk about your post turns to dismay as they start to tweet that your website is down — a database connection error is shown.
No need to be sad!
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