3 ms·

Can't help but think that this "logical clock" doesn't care simultaneity is relative. Ingenious!

• mjb 4y ago
  Yes, that's exactly right. Lamport clocks provide a partial ordering of events, based on the idea of "happened before". Specifically, Lamport defines the happens before operator →, such that within any one thread/process if a is done then b is done then a→b, and if a is one process sending c message and d is another process receiving the message then c→d. This allows a model where single-threaded processes communicate through messages, and allow us to reason about things like "if a could have caused b to happen, then a→b". Logical clocks are an extension of this model. This is covered in the classic "Time, Clocks" paper (https://www.microsoft.com/en-us/research/uploads/prod/2016/12/Time-Clocks-and-the-Ordering-of-Events-in-a-Distributed-System.pdf https://www.microsoft.com/en-us/research/uploads/prod/2016/1...). If you read exactly one distributed systems paper in your life, it should probably be this one.
  • mjb 4y ago
    Bonus all-time great paper review: "Jim Gray once told me that he had heard two different opinions of this paper: that it’s trivial and that it’s brilliant. I can’t argue with the former, and I am disinclined to argue with the latter." (from Lamport at https://www.microsoft.com/en-us/research/publication/time-clocks-ordering-events-distributed-system/?from=http%3A%2F%2Fresearch.microsoft.com%2Fen-us%2Fum%2Fpeople%2Flamport%2Fpubs%2Ftime-clocks.pdf https://www.microsoft.com/en-us/research/publication/time-cl...).
• dboreham 4y ago
  It was inspired by relativity, the Einstein kind.