Reactive diffracting trees

Giovanni Della-Libera*, Nir Shavit

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review


Shared counters are concurrent objects which provide a fetch-and-increment operation on a distributed system and can be used to implement a variety of data structures, such as barriers, pools, stacks, and priority queues. Diffracting trees are novel data structures that provide an effective, high throughput and low contention, shared counter construction. Under high loads, their performance has been shown to surpass all known counter implementations. Unfortunately, Diffracting trees of differing depths are optimal for limited load ranges, and a deep tree that performs well under high load performs rather poorly when the load is very low. To overcome this drawback, we introduce the Reactive Diffracting Tree, a novel Diffracting tree construction which can grow and shrink as necessary to better handle the changing access patterns and memory layout of the machine on which it runs. It provides true scalability and locality by dynamically `morphing' itself all the way from a simple queue-lock based counter under low load, through a range of increasingly deeper/shallower Diffracting trees as the load varies. Empirical evidence, collected on a 32-node Alewife cache-coherent multiprocessor and the Proteus distributed shared-memory simulator, shows that the reactive diffracting tree provides throughput within a constant factor of optimal depth Diffracting trees at all load levels. It also proves to be an effective competitor with known randomized load balancing algorithms in producer/consumer applications.

Original languageEnglish
Number of pages9
StatePublished - 1997
Externally publishedYes
EventProceedings of the 1997 9th Annual ACM Symposium on Parallel Algorithms and Architectures, SPAA - Newport, RI, USA
Duration: 22 Jun 199725 Jun 1997


ConferenceProceedings of the 1997 9th Annual ACM Symposium on Parallel Algorithms and Architectures, SPAA
CityNewport, RI, USA


FundersFunder number
National Science FoundationCCR-9225124
Defense Advanced Research Projects AgencyCCR-9520298, 03610882, F19628-95-C-0118
Israel Science Foundation
Ministry of Science and Technology, Israel


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