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Distributed Computing

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Originally published in Queue vol. 13, no. 3
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(newest first)

dcstayyc | Thu, 16 Jul 2015 06:10:19 UTC

I enjoyed reading this article. It soothes my frustration with papers that use global (logical) time for their definitions (e.g. the use of "simultaneous" to define deadlocks, mutual exclusion, etc.); to me, a theory or an algorithm that is based on a dodgy concept is surely bug-prone.

As you said, relativity isn't the problem here, since the issue arises even on a chip, where signals take many cycles to travel between cores and caches. A read or write operation therefore has a time spread at a core that is different from that at a cache, but this difference remains missing from most papers on sequential consistency, linearizability, etc.

I hope you have better luck nudging people off the global time concept.

JF | Thu, 26 Mar 2015 15:15:18 UTC

Very interesting article. Thank you.

For another system that deals with the "Now" problem, operating in an even more extreme environment, yet still reaching distributed consensus, have a look at Bitcoin. Granted, it doesn't reach consensus in milliseconds, rather on the order of 10 minutes, but interesting nonetheless.

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