Efficient lock free privatization

Yehuda Afek*, Hillel Avni, Dave Dice, Nir Shavit

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Working on shared mutable data requires synchronization through barriers, locks or transactional memory mechanisms. To avoid this overhead a thread may privatize part of the data and work on it locally. By privatizing a data item a thread is guaranteed that it is the only one accessing this data, i.e., that it accesses the data item in exclusion. The most robust and yet lock-free privatization algorithms, are lock-free reference counting (LFRC). These algorithms attach a counter to each node, which counts the number of references to the node. However, these counters are shared by all threads in the system and thus are contention prone, and must be updated with expensive atomic operations such as CAS. We present a new privatization algorithm, Public Guard (PG); an algorithm which eliminates most of the contention of LFRC algorithms, while maintaining their robustness and non blocking nature. Our evaluation shows that PG improves performance by up to 50% in many work loads. Another problematic issue with LFRC, that we address in this paper, is that a counter of a private node, may be accessed by a slow thread. This may prevent LFRC from freeing memory to the system. In another contribution of this paper we suggest a method with minimal overhead to allow LFRC to reclaim memory.

Original languageEnglish
Title of host publicationPrinciples of Distributed Systems - 14th International Conference, OPODIS 2010, Proceedings
Number of pages15
StatePublished - 2010
Event14th International Conference on Principles of Distributed Systems, OPODIS 2010 - Tozeur, Tunisia
Duration: 14 Dec 201017 Dec 2010

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume6490 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference14th International Conference on Principles of Distributed Systems, OPODIS 2010


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