mBrace: Action-Based Performance Monitoring of Multi-tier Web Applications

Today´s monitoring tools and Web application middleware offer very limited support for detailed performance analysis of HTTP request-based, multi-tier Web applications. They measure resource usage system-wide or per command name, but are unable to isolate usage per action specific to the target application. This inability has several causes: First, many HTTP requests are executed by one application or script simultaneously, making it hard to isolate them. Second, it is difficult to monitor at the granularity of a thread, while efficient Web servers and database servers implement thread-based process models. Third, different types of actions are often handled by one application or script, hindering type-based distinction. Finally, existing tools are often interval-based, consequently missing short-lived processes that live between two capturing points. The same limitations apply to measuring individual SQL queries. In addition, SQL queries cannot be backtracked to the HTTP request that triggered them, even though they frequently turn out to be the cause of long end-to-end response times. This paper describes a preliminary solution that addresses these problems and enables us to measure resource consumption and database interaction for individual actions, in real-time and under load, with minimal effort from the Web application developer.