Three Questions for Leslie Lamport, Winner of Computing’s Top Prize

by Tom Simonite, MIT Technology Review 

This year’s Turing Award honors algorithms that underpin everything from cloud computing to multicore processors.

In an interview, 2013 ACM A.M. Turing Award winner Leslie Lamport discusses distributed computing, with particular emphasis on its importance and longevity.

Lamport notes his Byzantine Generals work on imbuing software with fault tolerance stemmed from a contract in which he had to build a reliable prototype computer for flying aircraft for the U.S. National Aeronautics and Space Administration. The possibility of multiple systems failing made a distributed system necessary, and Lamport notes computers with multiple processors also constitute distributed systems.

He attributes the long-term endurance of his distributed-computing algorithms to consistent basic ideas about synchronization. “Running multiple processes on a single computer is very different from a set of different computers talking over a relatively slow network, for example,” Lamport says. “[But] when you’re trying to reason mathematically about their correctness, there’s no fundamental difference between the two systems.”

Lamport stresses that prior to coding, programmers should understand what they are doing and write it down. He says most code is written without a blueprint or specification, and he blames the software culture for this gap and suggests the use of mathematics to correct it. Read the interview

DCL: with all the innovations in modern software languages, he’s right that “programing with specifications” is not yet standard practice. His early paper “Time, Clocks, and the Ordering of Events …” bears rereading today, http://research.microsoft.com/users/lamport/pubs/time-clocks.pdf