Load Testing Blog
Validate the Testcases
When a website is placed under heavy load, it can fail in a wide variety of ways. The site may become unresponsive or return an HTTP status code indicating an error (500). Or it might return a web page that is mostly complete (the headers, footers and navigation are all present) but is missing a critical part that was related to the failure.
If the load test scenarios (testcases) do not validate page content well enough to catch these problems, the results could be misleading. I.e. the system could be failing but the results … Continue reading »
Test Only as Accurately as Needed
In previous posts, I’ve talked a lot about the dangers of not accurately simulating the real-world usage. But there is another side to this story: obsessing too much over an accurate simulation can be very costly. There is one very important thing to understand about load testing: No matter how hard we strive to make tests accurate, they are still only an estimate.
Your load test will never match even one single hour of production usage, not even once, no matter how hard you try. Bold statement? Perhaps. Consider this: even … Continue reading »
Troubleshooting Obsolete License Error
So your license is obsolete, what exactly does that mean? By default a Load Tester license is not set to expire unless it is a temporary license. An obsolete license essentially means that the license version does not match the Load Tester version number.
When a license is mismatched, the following message appears:
As you can see on the License Key Summary, the version code is listed as 4.2, however the current version of Load Tester I have installed is 4.3.
When a license shows up as obsolete, you have two options:
Match … Continue reading »
Identify and Test High-Risk Operations
As I described in my previous post on choosing test scenarios, the early tests should focus on the high-traffic scenarios. After testing and optimizing those, the next step is to identify and test the rarely-used but high-risk operations. These are operations that may have an impact on performance that is not proportional to their frequency. Even though these are not as common, they can have large impacts due to their system-wide nature and can cause sporadic performance drops during production hours that defy explanation.
Examples include:
Complex searches
Updates that touch many joined … Continue reading »
Design a Load Test that Measures What You Really Want to Know
When the first few testcases are ready, the next step is to put them together into a load test. How they are combined and executed will have a big impact on the accuracy of the test.
Testcase ratios – Make sure that each testcase is exercised in the correct ratio relative to the other testcases. For example, it is likely that many more people will be searching for products than buying them – the load configuration should reflect this ratio.
Page ratios – Re-visit the hit … Continue reading »
Build Realistic Testcases
When you have identified the first group of scenarios to test, it is time to turn them into testcases, which is the term we use for the representation of the scenario in software. In it’s simplest form, a testcase is a list of pages to visit. In the simplest tools, it may simply be a list of URLs. With most tools, the testcase is a program generated by the tool and customized by the tester. More sophisticated tools, such as Load Tester, present the testcase … Continue reading »
Understanding the Page Grouper
One of the key capabilities of Web Performance Load Tester is the page grouper. This is one of those systems for which, the fewer people notice it, the better it is performing. Essentially the page grouper takes a long list of HTTP transactions in a test case and organizes them, using timing, and/or content and referrer analysis, into a series of logical pages.
If we do this well, we assume that the list of pages we see in a test script after a recording are the same as the logical pages an end … Continue reading »
Recording in Load Tester: What’s Going On?
Draft
Load Tester is designed to recognize common use patterns and transform them into working test cases with a minimum of user intervention. Our clients appreciate that Load Tester does a tremendous amount of work automatically. But, any load testing tool must be prepared to exercise the complexity of its target, and for some web applications even a simple test case can involve hundreds of variables.
This post will try to elucidate the stages of the recording process, which are, roughly:
Recording
Initial Inspection
Automatic Configuration
Manual Configuration
Replay
Validation
During the recording stage, we manually perform a … Continue reading »
Web Performance, Inc Boosts SHRM Website Capacity by 2,000 Percent in Time for Launch
Society for Human Resources Management website able to service its 250,000 members while introducing potential savings of $200,000.
Durham, NC – February 19, 2009 – The new Society for Human Resources Management (SHRM) website was recently given a huge capacity boost in time for its unveiling, enabling the site to handle large amounts of traffic from its 250,000 members. Web Performance, Inc., (WPI) developers of industry-leading Web Performance Load TesterTM software, increased the site’s capacity from 100 to 2000 users, and reduced server … Continue reading »
Functional test suites do NOT make good load tests!
Functional test suites do NOT make good load tests! Functional test suites have an inherently different purpose than performance test suites. It is always tempting to take your suite of functional tests and use that as the basis for your load test. This is especially true if your testing tool supports both functional and load testing.
The purpose of functional testing is to determine if the site works correctly. As every good tester knows, this means testing the edge cases. What happens when the user does something unexpected? … Continue reading »
