A Monitoring Language for Run Time and Post-Mortem Behavior Analysis and Visualization

UFO is a new implementation of FORMAN, a declarative monitoring language, in which rules are compiled into execution monitors that run on a virtual machine supported by the Alamo monitor architecture. FORMAN's event trace model uses precedence and inclusion relations to define a DAG structure that abstracts execution behavior. Compiling FORMAN rules into hybrid run-time/post-mortem monitors gives substantial speed and size improvements over pure post- mortem analyzers that operate on the event trace DAG. The UFO optimizing compiler generates code that computes, at run-time when possible, the minimal projection of the DAG necessary for a given set of assertions. UFO enables fully automatic execution monitoring of realistic size programs. The approach is non-intrusive with respect to program source code. The ability to compile suites of debugging and program visualization rules into efficient monitors, and apply them generically to different programs, will enable long- overdue breakthroughs in program debugging automation.