City Research Online

Abstract

van Emde Boas (vEB) trees are sequential data structures optimized for extremely fast predecessor and successor queries. Such queries are an important incentive to use ordered sets or maps such as vEB trees. All operations in a vEB tree are doubly logarithmic in the universe size. Attempts to implement concurrent vEB trees have either simplified their structure in a way that eliminated their ability to perform fast predecessor and successor queries, or have otherwise compromised on doubly logarithmic complexity. In this work, we leverage Hardware Transactional Memory (HTM) to implement vEB tree-based sets and maps in which operations are doubly logarithmic in the absence of contention. Our proposed concurrent vEB tree is the first to implement recursive summaries, the key algorithmic component of fast predecessor and successor operations. Through extensive experiments, we demonstrate that our algorithm outperforms state-of-the-art concurrent maps by an average of 5× in a moderately skewed workload, and the single-threaded C++ standard ordered map and its unordered map by 70% and 14%, respectively. And, it does so while using two orders of magnitude less memory than traditional vEB trees.

Publication Type:	Conference or Workshop Item (Paper)
Additional Information:	© 2024 Copyright held by the owner/author(s). Publication rights licensed to ACM. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from permissions@acm.org.
Publisher Keywords:	Concurrent Data Structures, vEB Trees, van Emde, Boas Trees, Transactional Memory, Lock Elision
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science Q Science > QA Mathematics > QA76 Computer software
Departments:	School of Science & Technology School of Science & Technology > Department of Computer Science
SWORD Depositor:	Symplectic Administrator

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