Tham khảo tài liệu 'assembly language: step-by-step - part 14', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 608 Chapter 14 before the change was made to the slowest speed with the change the speed has increased by over 180 times. After this change it s time to run ACT to see what kind of performance can be obtained on the tests that were defined. The original test was run with three browser connections because that was the only test that did not generate errors. The result of the new test also had no errors. Figure shows the difference between the two tests. Comparing the graph of the original test against the new test shows a substantial difference in performance. Neither of these tests generated errors. What was once an extremely slow site now responds significantly better. The original test delivered a mere 12 responses whereas the latest test delivered 2 204 responses. This is over 180 times the original test. Caching Caching data can result in substantial performance gains. In situations where many users would normally make calls to the database for data that rarely changes caching the data on the Web server can completely bypass the call to the database server. The cache has a global scope and includes the necessary locking mechanism to allow items to be added and read from the cache by many users. Caching specifics are covered in more detail in Chapter 12 Applications. This section explores some of the performance gains derived from caching. Figure The original three-browser connection test overlaid with a new three-browser connection test. Performance Tuning and Application Instrumentation 609 Page Caching Page caching is probably the easiest caching method to implement. This is a compelling choice for many Web applications. To enable Web page caching the following information must be added to the HTML at the top of the Web page @ Outputcache Duration 60 VaryByParam customerId pageNumber This setting caches the page output for 60 seconds after which the cache is invalidated and the next request for the page results in .
