Cyclic Debugging for pSather, a Parallel Object-Oriented Programming Language

The paper discusses the main aspects of a parallel debugger for the parallel object-oriented language pSather. PSather provides for a single shared-address space and for multiple threads per processor. Threads can arbitrarily migrate between processors. The debugger supports cyclic debugging which is a standard and quite effective technique for sequential programs. To address nondeterminism, deterministic replay is provided. For that reason, one program run is traced. The debugger uses these traces to repeatedly and identically reexecute the recorded program run. An efficient trace and replay scheme that is in particular suited for pSather and that reduces program perturbation and trace file length is presented. Furthermore, breakpoints and single-stepping for such a debugger using deterministic replay are discussed.