Debugging parallel programs using event graph manipulation

The need for more accurate results and larger problem sizes pushes the users in certain fields towards using supercomputing power. Besides problems with initial program development, another problem arises with debugging this kind of program. Debugging parallel programs is one of the hard tasks that users have to deal with when using parallel architectures. Where memory hot spots and bus contention are problems with shared memory architectures, nondeterminism arising from race conditions and the lack of a global clock are severe problems in using distributed memory architectures. We will discuss a new approach for detecting and/or studying concurrent events in distributed memory machines if race conditions occur in a certain program run. Through event graph manipulation the user can investigate whether wrong results may appear through different ordering of events.