Time, Clocks, and the Ordering of Events in a Distributed System Alive
Time, Clocks, and the Ordering of Events in a Distributed System
KindPaper
Published1978
StatusAlive
AuthorsLeslie Lamport
FieldConcurrency
Logical clocks and happened-before — the paper that taught distributed systems to think about causality. Its most-cited claim: mutual exclusion needs no physical time.
1960198020002020
Created by Leslie Lamport
Submitted in 1976, published in CACM in July 1978, the paper introduced the happened-before partial order — events ordered by causality, not wall time — and logical clocks implementing it. Lamport proved a distributed mutual-exclusion algorithm with it.
It is the most-cited paper in distributed computing: vector clocks, causal consistency, and modern consensus reasoning all descend from its framework. Lamport has said the idea came from trying to understand spacetime; distributed systems got the benefit.