דניאל הנדלר

The non-blocking work-stealing algorithm of Arora, Blumofe, and Plaxton (hencheforth ABP work-stealing) is on its way to becoming the multiprocessor load balancing technology of choice in both Industry and Academia. This highly efficient scheme is based on a collection of array-based deques with low cost synchronization among local and stealing processes. Unfortunately, the algorithm's synchronization protocol is strongly based on the use of fixed size arrays, which are prone to overflows, especially in the multiprogrammed environments which they are designed for. This is a significant drawback since, apart from memory inefficiency, it means users must tailor the deque size to accommodate the effects of the hard-to-predict level of multiprogramming, and add expensive blocking overflow-management mechanisms. This paper presents the first dynamic memory work-stealing algorithm. It is based on a novel way of building non-blocking dynamic memory ABP deques by detecting synchronization conflicts based on "pointercrossing" rather than "gaps between indexes" as in the original ABP algorithm. As we show, the new algorithm dramatically increases robustness and memory efficiency, while causing applications no observable performance penalty. We therefore believe it can replace array-based ABP work-queues, eliminating the need to add application specific overflow mechanisms.