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Accelerate web applications with Varnish Cache

Horsepower

Article from ADMIN 51/2019

By Stefan Wintermeyer

If a web application delivers its pages too slowly, users quickly move on. Varnish Cache lets you hitch more horses to the cart.

Successful web applications grow organically and eventually reach the point where a speed bottleneck occurs in the system. Websites that are too slow usually have high bounce rates. Sometimes, they also suffer involuntary denial of service attacks by normal visitors who continuously click Refresh or Reload if load times are too long.

Because the professional environment often dictates the programming language and the framework used, whether the bottleneck happens sooner or later is out of the developer's hands. (See the "Classic" boxout.) However, with the programmable caching HTTP reverse proxy Varnish Cache, you can speed up the delivery of web pages with performance that is usually limited only by the speed of the network itself.

Classic

Apart from optimizing the cache functions in the stack, you should always look for classic programming errors. Pitfalls large or small are often hidden in legacy code. If you get rid of them, the stack will reward you with significantly more performance than all the subsequent caching could ever offer.

If a website becomes too slow and the bottleneck is the web application server that generates the HTML code, the usual solution is more or faster hardware. If the web application runs on a hosting service like Amazon Web Services or Heroku, you can solve the problem through liberal use of your credit card. Once the latter is exhausted, or if the cloud is not an option or is against your problem-solving principles, the search for better solutions begins.

Whodunit?

To understand a performance problem, you first need to trace the chain from the web browser query to the record. Web applications usually store data in an SQL database. The web application, often written in PHP, Python, or Ruby, grabs this

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