As the use of complex grid middleware becomes widespread and more facilites are offered by these pieces of software, distributed Grid applications are becoming more and more popular. But as Grid middleware grows in size and offers more advanced features, they become more complex and heavier, as well as harder to tune. Since the performance of a distributed Grid application can be strongly influenced by the operation of the underlying grid middleware, it becomes of extreme importance to study and analyse its behaviour and performance.

In this paper we present the eDragon Monitoring Framework (eDMF), a set of tools that can be used for the instrumentation and analysis of grid middleware, and which provides a unique environment to study the performance of Grid applications. The eDMF is composed of a set of specialised monitoring tools as well as by a flexible and powerful performance analysis platform. Additionally we also provide a practical application of the eDMF to the Globus Toolkit 4 (GT4), one of the most extended and popular Grid middleware, showing how it helped us in the detection and resolution of several job management problems observed in the GT4 middleware.