Speed Up Your Web Site with Varnish Varnish is a program that can greatly speed up a Web site while reducing the load on the Web server. According to Varnishs official site, Varnish is a Web application accelerator also known as a caching HTTP reverse proxy. When you think about what a Web server does at a high level, it receives HTTP requests and returns HTTP responses. In a perfect world, the server would return a response immediately without having to do any real work. In the real world, however, the server may have to do quite a bit of work before returning a response to the client. Lets first look at how a typical Web server handles this, and then see what Varnish does to improve the situation. Although every server is different, a typical Web server will go through a potentially long sequence of steps to service each request it receives. It may start by spawning a new process to handle the request. Then, it may have to load script files from disk, launch an interpreter process to interpret and compile those files into bytecode and then execute that bytecode. Executing the code may result in additional work, such as performing expensive database queries and retrieving more files from disk. Multiply this by hundreds or thousands of requests, and you can see how the server quickly can become overloaded, draining system resources trying to fulfill requests. To make matters worse, many of the requests are repeats of recent requests, but the server may not have a way to remember the responses, so its sentenced to repeating the same painful process from the beginning for each request it encounters.
Posted on: Fri, 19 Sep 2014 19:54:12 +0000