If you do not already have a performance testing tool and are doing HTTP or HTTPS development then I would recommend that you look at OpenSTA. The tool is open source, and so the only up front cost involved is the time it takes to learn the interface and produce scripts. It isn’t the only open source load testing tool out there, but it has a strong combination of simplicity of use and scripting flexibility.
It provides a record-playback interface, and the generated scripts can then be customised using a simple basic-like language. It can also gather performance monitoring data from the load testing environment. For Windows machines the capture data can come directly from any of the performance monitor counters available on the system. For other operating systems, can be monitored using SNMP-based counters. This is slightly more complicated, but is feasible without too much difficulty.
It can also be used to simulate high loads, with a network of load generation machines being able to be controlled from a single master machine. Depending on the specification of the systems and the script involved each load machine can generate over 1,000 simulated users. Thus even very high user loading levels can be simulated using the tool without incurring excessive costs. To put this in context, the cost of using commercial software to simulate load usually increases with the number of connections being simulated.
Lastly on the feature set, the tool has a set of relatively simple analysis reports that are built into it. These allow some of the most common performance analysis questions to be answered almost immediately. If these built in reports aren’t sufficient, however, the raw data can be exported to Excel and analysed there. This allows analysis such as a percentile-based examination of response times.
Like any software tool it does have its difficulties and limitations. One of these is that it is a Windows tool, and requires Excel to be installed to get the best out of it. The user interface and scripting language also have limitations and frustrations. Probably the most important limitation is that it doesn’t support the range of protocols that the more expensive tools do. Thus, if you need support for testing a range of protocols you will need to look elsewhere. If what you need is a web testing tool without excessive costs, however, I can recommend starting here and choosing a full commercial tool only if you find you really need it.
If you need help in choosing or using suitable tools for performance management work, whether open source or commercial tools, then e-mail me. The choice of tool, and the way it is used, will make a big difference to the results and time required for a performance management initiative.