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Author Archives: Ivan Lisitsyn
Performance glitches on charts
When you load test a web application and gradually increase the number of virtual users during the test, you usually expect to see gradually degrading performance parameters such as response time. The number of pages (sessions or hits) per second will reach maximum in some moment and will probably stay the same for the rest of the test despite the growing load. This is simply because the site cannot serve more requests per second, so it has to postpone the new coming ones.
In reality you will probably see something like that, but only for a limited time. When the load goes even higher, you can get another picture that may seem surprising at first glance. It is illustrated by the following three charts. Black line in all charts represents the number of virtual users. Continue reading
Posted in Testing practice, WAPT usage
Tagged error rate, load test, performance testing, response time
1 Comment
How to analyze a load test report? Part 4: Response time.
Let’s suppose that you have already resolved all problems related to unexpected errors in your test. I mean that your site may produce some errors on heavy load, but the emulation of the user sessions is performed correctly and the error rate is acceptable. If this is not the case, or you have any doubts, you may want to read my earlier posts here and here.
If the errors are not an issue, your next step is to look at the most evident indicator of the application performance – its response time. This term initially refers to a time required for your application to respond to a user action. This looks very simple, but you should keep in mind the following things, if you want to analyze the test results correctly.
Posted in Testing practice, WAPT usage
Tagged load test, performance testing, response time, test report
15 Comments
Connecting to WMI on a remote system
Windows Management Instrumentation (WMI) is one of the common interfaces used to retrieve information from a Windows system. Such information can include values provided not only by the system itself, but by various software programs running on it. That is why WMI is widely used to monitor the performance and correct operation of the server components.
Many load testing tools, such as WAPT Pro, can monitor performance counters directly from the tested servers with help of WMI. The most useful counters are those representing CPU, RAM and network usage, but there can be other server-specific ones that you can easily retrieve. Continue reading
How to analyze a load test report? Part 3: Errors.
If you see any errors after executing a load test, first of all you should check if this is a test design problem. I wrote about the most typical problems of that kind here.
Now let’s suppose that the test was designed correctly and any errors we see in the report are related to the load you created in the test. In other words, I would like to talk about errors that appear because of performance problems, not anything else. If you are not sure why an error takes place, try running the test with same profiles and a smaller number of users, and see if the same problem appears.
First of all I should note that there are different types of errors. Continue reading
WAPT Cloud: New benefits of our load testing solution
In the last days of 2013 we released a cloud version of our load testing solution. It is based on WAPT Pro, all extension modules and x64 Load Engines, so it is the most feature-reach and powerful combination of all the components we have.
This on-demand load testing solution is offered through the Amazon EC2 Marketplace. This means that with few clicks you can get the full functionality of WAPT Pro running on a virtual system instance in the Amazon Cloud. To do this you need to have an AWS account, however it is also very easy to create one. We provide step by step usage instructions right from our web site.
Some experienced users already know that all our products can be used in any cloud or virtual environment. So, technically this release is not a big step forward. With new cloud version it is easier to start and configure the product, but this is not the actual benefit. What really makes the change is the pricing for the new solution, which is now based on the hour rates. Continue reading
How to setup SNMP monitoring of a Windows system
SNMP (Simple Network Management Protocol) is a network protocol that allows one device to query another device for information, change information on a device, or for one device to send a message to another device. It is widely used to monitor hardware and software components of web sites during normal operations or during testing. That is why advanced load testing tools, such as WAPT Pro, usually have ability to connect to any servers and receive performance counters data (such as CPU or RAM usage values).
Older versions of Windows, like XP, had SNMP service installed by default, so you only had to start it or enable automatic start. After that you could connect to that system with any SNMP client and monitor anything you needed. Continue reading
How to setup Oracle monitoring in WAPT Pro
WAPT Pro can monitor the performance of database servers during the test. This is useful in case your web application uses a database running on a separate server and you want to check if that database can be a performance bottleneck.
Each database has a special table with performance parameters (such as the number of transactions completed per second, number of threads, etc.). To retrieve any specific parameter you need to execute the corresponding SQL statement. So, this is done the same way as any other data retrieval. The only difference is that performance parameters are calculated by the database server itself. You do not need to create the performance table before using data from it.
Continue reading
How to analyze a load test report? Part 2: Test design problems.
When you start load testing a web site (especially if this is the first load test in your life) you may see a lot of errors in the report. Possibly you will even have to stop the test before it completes, because at some point in time it becomes clear that something goes wrong. If the problem is not so obvious, it is still recommended to check the report for the errors related to each virtual user profile (i.e. to each different type of virtual users) before looking at any performance data.
Usually you do not create a high load in the very first test of a web site, so if you see any errors in the report, most probably they appear because of the test design problems. In other words, the emulation of the real user activity is performed incorrectly. Your web application may produce errors and even refuse connections because it receives incorrect data from your load testing tool. Why this may happen?
Continue reading
Posted in Testing practice, WAPT usage
Tagged error type, HTTP status code, parameterization, test execution log, test report
5 Comments
New release: WAPT 8.1 and WAPT Pro 3.1
We are proud to announce the release of new versions of our products: WAPT 8.1 and WAPT Pro 3.1. This upgrade is free for all registered users of WAPT 8.0 and WAPT Pro 3.0 correspondingly. So, if you already have a license, you can download new versions and update your installation.
Note that load agents and x64 Load Engines should be also updated for use with the latest version of WAPT Pro.
Even though formally this is a minor upgrade, new versions have a number of features that really make the difference. Now I would like to mention couple technical details about the features that I treat as the most important. Continue reading
Posted in WAPT usage
Tagged new release, parameterization, performance counters, recording test
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