Coding the Architecture - loadtesting tag

Stating the obvious

Tue, 16 Jun 2009 14:08:33 GMT

If you've watched A developer's guide to load testing, you will have seen the graph below already. It shows the results from load testing a website written in .NET with the Apache JMeter load testing tool. Along the bottom of the graph are the actions that make up the load test script, while the vertical axis is the response time in seconds. Each line represents the results from a different test run with a different number of concurrent users.

The interesting thing about this graph is that the average response time for any page request is just a few seconds, with the exception of the spike around a third of the way in. This spike is caused by the .NET web tier having to aggregate information from several calls to a backend system, where some resource locking bottlenecks the incoming requests. From analysing the load testing environment during the test run, we were able to ascertain where the hotspot was because (a) the CPU load for the web-tier dropped off when this call was taking place and (b) we could see the requests being queued up on the backend system. From a technical perspective then, load testing is a fantastic way to find and highlight bottlenecks in the overall architecture, providing an opportunity to present some real evidence about the performance degradation and where the hotspots are.

Furthermore, in this example there was a general feeling that this particular action was slow, but the evidence was only empirical. People had experienced this slowness but had never actually measured it before. Kevin made a comment during the last user group where he mentioned that the architect sits between the technical and business spaces, spanning the two and bringing them together. Raw results from a load test are one thing, but presenting the data in a way that makes sense to non-technical people can tell a completely different story. Sometimes your load testing results state the obvious, but sometimes they don't.

A developer's guide to load testing - video

Mon, 15 Jun 2009 22:27:51 GMT

Just a quickie ... the video from A developer's guide to load testing at Skills Matter last week is now available to view online. The microphone picked up the questions and comments quite well, which is excellent. Enjoy, and feel free to use the Google Group to continue the discussion.

Thanks again to Skills Matter.

A developer's guide to load testing - slides

Thu, 11 Jun 2009 18:40:49 GMT

Thanks to everybody that came along to the CTA user group earlier in the week. The tube strike may had reduced the numbers but we still had some great discussion about load testing. My slides are available to download (~4MB) and if anybody wants to continue the discussion, please feel free to use the Google Group.

A developer's guide to load testing (PDF, ~4MB)

I'll post an update when the Skills Matter podcast/video is available to view online.

A developer's guide to load testing

Tue, 02 Jun 2009 08:39:00 GMT

Here are the details of the June 2009 London User Group.

Title : A developer's guide to load testing
Summary : Load testing is an often forgotten and seemingly difficult task that many people shy away from doing. It doesn't have to be this way though, with a basic level of load testing often enough to give you confidence that you've satisfied your non-functional requirements around performance and scalability. This session will look at load testing a website from a developers perspective. We'll look at the differences between load testing, stress testing and soak testing along with a hands-on demonstration of an open source load testing tool that you can use to get started. If you're building websites in Java, .NET, PHP or indeed any other programming language, this session will show you how easy it is to load test your website.
Date : Tuesday, 9th June 2009
Time : 18:30-20:00
Location : Skills Matter, 1 Sekforde Street
Format : Presentation and discussion, with further discussion in a local pub (The Crown).
Cost : Free, but registration is required.

Many thanks to Skills Matter for sponsoring the user group.

p.s. this session is being run after the second day of our software architecture training at Skills Matter in London ... there are a couple of places left if you want to come along and learn about software architecture.