Time, clocks, and the ordering of events in a distributed system
Open accessAbstract
The concept of one event happening before another in a distributed system is examined, and is shown to define a partial ordering of the events. A distributed algorithm is given for synchronizing a system of logical clocks which can be used to totally order the events. The use of the total ordering is illustrated with a method for solving synchronization problems. The algorithm is then specialized for synchronizing physical clocks, and a bound is derived on how far out of synchrony the clocks can become.
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CRDT convergence already provides the safety property advisory claims need; causality is established by the underlying CRDT which inherits Lamport's happens-before for ordering concurrent edits, in contrast to the operational-transformation lineage that requires a central transformation server.
“CRDT convergence already provides the safety property advisory claims need; causality is established by the underlying CRDT [Shapiro et al., 2011] which inherits Lamport's happens-before [Lamport, 1978] for ordering concurrent edits, in contrast to the operational-transformation lineage [Ellis and Gibbs, 1989, Sun et al., 1998] that requires a central transformation server.”
From AgentRoom: Concurrent Multi-Agent Coding in a CRDT-Backed Shared Workspace (2026) · cites this paper as Lamport, 1978
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Research works printed but not linked: 2
- Schwartz, J.T. Relativity in lllustrations. New York U. Press, New York, 1962.
- Ellingson, C, and Kulpinski, R.J. Dissemination of system-time. 1EEE Trans. Comm. Com-23, 5 (May 1973), 605-624.
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AgentRoom: Concurrent Multi-Agent Coding in a CRDT-Backed Shared Workspace
Cho, S., & Lee, D. (2026) · arXiv · doi:10.48550/arxiv.2608.23740
- Authors
- Lamport, L.
- Affiliations
- Massachusetts Computer Associates, Inc.
- Corresponding author
- Lamport, Leslie
- ORCID
- Lamport, Leslie
- Venue
- Communications of the ACM
- Published
- 1978-07
- Volume
- 21
- Issue
- 7
- Pages
- 558-565
- ISSN
- 0001-0782 (ISSN-L)
- 1557-7317
- OpenAlex
- W3137220996
- Cited by
- 8,488
- References
- 0
- Citations by year
- 2026: 108 · 2025: 117 · 2024: 122 · 2023: 131 · 2022: 121 · 2021: 212 · 2020: 217 · 2019: 305 · 2018: 303 · 2017: 261 · 2016: 304 · 2015: 293 · 2014: 308 · 2013: 309 · 2012: 284
- FWCI
- 33.54
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Communications of the ACM (publishedVersion)
- Topics
- Physical Sciences › Computer Science › Computer Networks and Communications › Distributed systems and fault tolerance
- Physical Sciences › Computer Science › Computer Networks and Communications › Network Time Synchronization Technologies
- Social Sciences › Decision Sciences › Management Science and Operations Research › Simulation Techniques and Applications
- Keywords
- event ordering, partial ordering, linear orders, logical clocks, physical clocks, clock synchronization, distributed algorithms, distributed systems
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