Upper and Lower Bounds on the Space Complexity of Detectable Objects

Ohad Ben-Baruch, Danny Hendler, Matan Rusanovsky

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

11 Scopus citations


The emergence of systems with non-volatile main memory (NVM) increases the interest in the design of recoverable concurrent objects that are robust to crash-failures, since their operations are able to recover from such failures by using state retained in NVM. Of particular interest are recoverable algorithms that, in addition to ensuring object consistency, also provide detectability, a correctness condition requiring that the recovery code can infer if the failed operation was linearized or not and, in the former case, obtain its response. In this work, we investigate the space complexity of detectable algorithms and the external support they require. We make the following three contributions. First, we present the first wait-free bounded-space detectable read/write and CAS object implementations. Second, we prove that the bit complexity of every N-process obstruction-free detectable CAS implementation, assuming values from a domain of size at least N, is Ω (N). Finally, we prove that the following holds for obstruction-free detectable implementations of a large class of objects: their recoverable operations must be provided with auxiliary state - state that is not required by the non-recoverable counterpart implementation - whose value must be provided from outside the operation, either by the system or by the caller of the operation. In contrast, this external support is, in general, not required if the recoverable algorithm is not detectable.

Original languageEnglish
Title of host publicationPODC 2020 - Proceedings of the 39th Symposium on Principles of Distributed Computing
PublisherAssociation for Computing Machinery
Number of pages10
ISBN (Electronic)9781450375825
StatePublished - 31 Jul 2020
Event39th Symposium on Principles of Distributed Computing, PODC 2020 - Virtual, Online, Italy
Duration: 3 Aug 20207 Aug 2020

Publication series

NameProceedings of the Annual ACM Symposium on Principles of Distributed Computing


Conference39th Symposium on Principles of Distributed Computing, PODC 2020
CityVirtual, Online


  • concurrent objects
  • detectability
  • non-volatile memory
  • recoverable algorithms

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Computer Networks and Communications


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