JI.FI: Visual test and debug queries for hard real-time

Hard real-time systems have stringent timing and resource requirements. As such, debugging and tracing such systems often requires low-level hardware support, and online debugging is usually precluded entirely. In other areas, visual debugging has greatly improved program understanding and late cycle development times for non real-time applications. In this paper we introduce a visual test and debug framework for hard real-time Java applications built around the JIVE platform and realized in the Fiji VM. Our framework, called JI.FI ["dZIfi], provides high-level debugging support over low-level execution traces. JI.FI provides both powerful visualizations and real-time centric temporal query support. To ensure preservation of the real-time characteristics of the application being tested and debugged, JI.FI leverages a real-time event log infrastructure that logs only relevant application and virtual machine level events, such as synchronization and modifications to priorities or thread state. Our performance results indicate that our logging infrastructure is suitable for hard real-time systems, as the performance impact is both uniform and quantifiable.