Java Enterprise Best Practices

Set Performance Targets

Regardless of where you are in your project, the first step in your performance plan should be to set performance targets. These should cover as many performance aspects as possible. Some of these include expected response times (e.g., “Any button click providing a new page should display in less than 2 seconds, except for queries . . . “), batch process times (e.g., “Nightly batch processing should not exceed 5 hours”), throughput (e.g., “The system should handle up to 60 transactions per minute within performance targets”), concurrency (e.g., “Up to 500 users can use the application at any one time”).

Performance in most projects is seldom consistent. All sorts of procedures can interrupt processes. For this reason, it is usually better to specify a range of acceptable performance targets—e.g., “Button click to page display response times should be less than 2 seconds in 90% of cases, and less than 5 seconds in 99% of cases.” When specifying response time ranges for activities initiated by users, pay special attention to the 90% range. Users’ perception of the average response times is actually close to the 90% value in the range of measured times. People give more weight to bad news, and their performance perceptions are no different.

Setting the performance requirements of your application is not necessarily a developer-level task. Your customers or business experts need to establish the response time that is acceptable for most functions the user will ...