Debugging with Transactional Memory

Transactional programming promises to substantially simplify the development of correct, scalable, and efficient concurrent programs. Designs for supporting transactional programming using transactional memory implemented in hardware, software, and a mixture of the two have emerged recently. To our knowledge, nobody has yet addressed issues involved with debugging programs executed using transactional memory. Because transactional memory implementations provide the “illusion” of multiple memory locations changing value atomically, while in fact they do not, there are challenges involved with integrating debuggers with such programs to provide the user with a coherent view of program execution. This paper shows how to overcome these problems by making the debugger interact with transactional memory implementations in a meaningful way. In addition to describing how “standard” debugging functionality can be integrated with transactional memory implementations, we also describe some powerful new debugging mechanisms that are enabled by transactional memory infrastructure. Our description focuses on how to enable debugging in software and hybrid software-hardware transactional memory systems.