Reliable Embedded Systems

A new paper from University of California, Berkeley, EECS professor Edward Lee has engineers buzzing about the potential of thread-based programming.

Multi-threaded programming primarily has been limited to single-core processors, and has performed fairly well, but multicore-chip vendors are now talking up multithreading as a way to take advantage of the processing power of their chips. Multithreaded applications are nondeterministic and very unintelligible to their own programmers, Lee writes in "The Problem With Threads," explaining further that program execution sequence and processor state can be switched at any time. As a result, programmers would never know whether every possible sequence is correct, which means bugs would be difficult to find, according to Lee, who is also a founder of Berkeley Design Technology. Although there are techniques for addressing the nondeterminism in some multithreaded applications, Lee maintains that the approach in flawed. He believes deterministic behavior should be the focus of programming methodology and languages, and that nondeterminism should be added when it is necessary.

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