Performance analysis for any application must be managed at every stage of the software-development lifecycle. Each of these stages use different performance management tools—profilers during coding and unit testing stages, load-testing tools during system validation and QA stages, and tools that deal with monitoring. During performance testing, however, analysis becomes a stumbling block when the system is subjected to production-like workloads and has a distributed operating environment. In this context, large amounts of information need to be monitored and analyzed to detect bottlenecks. The lack of automation in this diagnosis process motivated us to design and implement the tool for the .NET Framework that we present here. This tool lets you identify problematic areas, then helps you resolve bottlenecks in the .NET Framework during performance analysis. (The complete source code for the tool is available electronically; see "Resource Center," page 3.)

Our approach to diagnosis begins with the creation of a knowledge base comprising several performance patterns, which are indicators for detecting bottlenecks. We represent these performance patterns as a Bayesian network that has been extensively used in the field of medical diagnosis. A given scenario is diagnosed with respect to several performance patterns to report the possible problem areas or to comment on the scalability of the application.