CHAPTER 5 (Free web space) PERFORMANCE THROUGH THE APPLICATION DEVELOPMENT
CHAPTER 5 PERFORMANCE THROUGH THE APPLICATION DEVELOPMENT LIFE CYCLE executed sections of your code and those that account for the majority of the components execution times. The resulting relative weighting of hot spots in the code allows for intelligent tuning and code refactoring. You should run code profiling on your components while executing your unit tests, because your unit tests attempt to mimic end-user actions and alternate user scenarios. Code profiling your unit tests should give you a good idea about how your component will react to real user interactions. Coverage profiling reports the percentage of classes, methods, and lines of code that were executed during a test or use case. Coverage profiling is important in assessing the efficacy of unit tests. If both the code and memory profiling of your code are good, but you are exercising only 20 percent of your code, then your confidence in your tests should be minimal. Not only do you need to receive favorable results from your functional unit tests and your code and memory performance unit tests, but you also need to ensure that you are effectively testing your components. This level of testing can be further extended to any code that you outsource. You should require your outsourcing company to provide you with unit tests for all components it develops, and then execute a performance test against those unit tests to measure the quality of the components you are receiving. By combining code and memory profiling with coverage profiling, you can quickly determine whether the unit tests are written properly and have acceptable results. Once the criteria for tests are met, the final key step to effectively implementing this level of testing is automation. You need to integrate functional and performance unit testing into your build process only by doing so can you establish a repeatable and trackable procedure. Because running performance unit tests can burden memory resources, you might try executing functional tests during nightly builds and executing performance unit tests on Friday-night builds, so that you can come in on Monday to test result reports without impacting developer productivity. This suggestion s success depends a great deal on the size and complexity of your environment, so, as always, adapt this plan to serve your application s needs. When performance unit tests are written prior to, or at least concurrently with, component development, then component performance can be assessed at each build. If such extensive assessment is not realistic, then the reports need to be evaluated at each major development milestone. For the developer, milestones are probably at the completion of the component or a major piece of functionality for the component. But at minimum, performance unit tests need to be performed prior to the integration of components. Again, building a high-performance car from tested and proven high-performance parts is far more effective than from scraps gathered from the junkyard. Unit Testing I thought this section would be a good opportunity to talk a little about unit testing tools and methods, though this discussion is not meant to be exhaustive. JUnit is, again, the tool of choice for unit testing. JUnit is a simple regression-testing framework that enables you to write repeatable tests. Originally written by Erich Gamma and Kent Beck, JUnit has been embraced by thousands of developers and has grown into a collection of unit testing frameworks for a plethora of technologies. The JUnit Web site (www.junit.org) hosts support information and links to the other JUnit derivations.
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