How to cite a web site - application in the places that it’s already fast.
application in the places that it’s already fast. You need to use the tools to help you determine where the bottlenecks are. 17.4.3 Find the Trouble Areas Sometimes you get lucky and find the performance problems quickly. Other times, you need to use different tools to locate and isolate the areas that are causing the problems. This is where profiling tools can help. Profiling your application is somewhat different from conducting the performance tests that we’ve been discussing. Although performance tools might be able to tell you which web request took the longest to complete, they can’t tell you which Java method took up the most time. This is the purpose of profilers. Table 17-2 lists several profiling tools that can be useful in locating trouble areas of the application. Table 17-2. Commercially available profiling tools Company Product URL Rational Quantify http://www.rational.com Inprise OptimizeIt http://www.borland.com/optimizeit/ Sitraka Software JProbe http://www.sitraka.com Profiling an application is similar to debugging. You see where the application spends most of its time, how many calls are made to a specific function, how many objects are created, how much memory is used, and so on. You start from a high level and work your way down to the methods that are causing the performance or scalability problems. Once you fix the problem areas, you run the tests again. This is repeated until all of the problems are resolved, or until you have to ship the product. The performance tools can also help you determine where the problem areas are. In Figure 17-4, for instance, we see that the average transaction response time for one action seems much higher than those for the others. Figure 17-4. Higher average response times may indicate a problem
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