Can Data Flow Help Us Escape the von Neumann Machine?

Untangling code with flow-based programming

About a year ago I was struck by George Dyson‘s plea in his Strata London keynote

That’s why we live in this world where we follow this one particular [von Neumann] architecture and all the alternatives were squashed… Turing gave us this very powerful one-dimensional model, von Neumann made it into this two-dimensional address matrix, and why are we still stuck in that world? We’re fully capable of moving on to the next generation… that becomes fully three-dimensional. Why stay in this von Neumann matrix?

Dyson suggested a more biologically based template-based approach, but I wasn’t sure at the time that we were as far from three dimensions as Dyson thought. Distributed computing with separate memory spaces already can offer an additional dimension, though most of us are not normally great at using it. (I suspect Dyson would disagree with my interpretation.)

Companies that specialize in scaling horizontally—Google, Facebook, and many others—already seem to have multiple dimensions running more or less smoothly. While we tend to think of that work as only applying to specialized cases involving many thousands of simultaneous users, that extra dimension can help make computing more efficient at practically any scale above a single processor core.

Unfortunately, we’ve trained ourselves very well to the von Neumann model—a flow of instructions through a processor working on a shared address space. There are many variations in pipelines, protections for memory, and so on, but we’ve centered our programming models on creating processes that communicate with each other. The program is the center of our computing universe because it must handle all of these manipulations directly.

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Distributed resilience with functional programming

Steve Vinoski on when to make the leap to functional programming.

Functional programming has a long and distinguished heritage of great work — that was only used by a small group of programmers. In a world dominated by individual computers running single processors, the extra cost of thinking functionally limited its appeal. Lately, as more projects require distributed systems that must always be available, functional programming approaches suddenly look a lot more appealing.

Steve Vinoski, an architect at Basho Technologies, has been working with distributed systems and complex projects for a long time, first as a tentative explorer and then leaping across to Erlang when it seemed right. Seventeen years as a columnist on C, C++, and functional languages have given him a unique viewpoint on how developers and companies are deciding whether and how to take the plunge.

Highlights from our recent interview include:

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