Web Performance Tuning

Preface

When I told people I was writing a book called Web Performance Tuning, the usual response I got was that the title should be “Web Server Performance Tuning.” Most people believe that the server is the only part of the Web that you can tune. When you’re desperate to improve performance, however, you become much more creative about finding other parts of the Web that you can tune. You may not be able to do much about the public network or about remote clients, but you can tune entire intranet systems, including clients, networks, servers, and databases, and you can improve your access to the public network through better connections and strategic locations for clients and servers. Yes, you can tune the web server itself, but the server is only one piece.

Thinking in terms of individual machines is rapidly becoming obsolete. An isolated machine, whether PC or mainframe, is increasingly rare. There is a very good reason for this: a collection of machines is far more powerful, flexible, and reliable than any individual machine. The network takes on the characteristics of a bus connecting the components of a larger and better computer. To have a network connection to another machine is to have more power available from your own machine. To be connected to the Internet is to have access to millions of machines. The biggest disk in the world is simply all disks wired together.

What Is This Book Good For?

This book is good for improving web site performance, estimating web site hardware and software requirements, and clarifying scaling issues. It covers client and network issues as well as server-side issues, because many web sites are on intranets, where a system administrator has control over the client and network. While most web performance discussion centers on the HTTP server, the HTTP server itself is not usually the performance bottleneck. To improve performance, we must also look at other issues.

The performance I care about is from the end user’s point of view: how quickly the Web satisfies the user’s request. There are other kinds of performance, such as total server throughput or availability, but this book focuses on the user’s perception of speed.

Although it presents some general principles of performance tuning, this book concentrates on practical advice much more than on theory. The principles are presented only to show patterns that unify typical web performance problems and solutions. While any book on performance tuning is to some degree a collection of tips and tricks, I hope the principles help to bring some order to this collection.

Another goal of this book is to present a clear picture of the chain of events involved in viewing a web page. Having a clear mental model of exactly what happens and why is critical to reasoning through new performance problems and finding solutions.

In the end, performance tuning is about spending money and time wisely to get the most out of your resources. A lot of life is like that.