1. David Callahan Distinguished Engineer Parallel Computing Platform Team Visual Studio Microsoft

2. design patterns Programming languages capture design patterns Function calls/return Objects/Method Dispatch/Interfaces/Generics in Higher-order Functions in C# versus versus Iterators (CLU versus C++ versus C#) Access to structured data (LINQ) Design patterns change over time Increasing complexity with new abstraction conventions Domain-specific uses (Snobol, MATLAB, php, Ruby) New programmer burdens But the new interoperates with the old… Language constructs support application lifecycle Architecture/development (modules, namespaces, packages) Testing (especially defect analysis/SAL) Performance analysis (especially “the dialog”) Maintenance 3/12/2007CGO-20072

3. A least three design patterns demand support Services (a.k.a. Actors, CSP) – asynchronously evolving agents with private state communicating via messages Forall – (opportunistic) nested data parallelism over partially-ordered slices of data collections Array languages/Parallel LINQ/and sharper knives Transactions – unordered updates to shared state And this ignores locality…. Chapel/X10/Fortress Language bindings facilitate engineering automation Load balancing Resource management Speculation/Deadlock-recovery 3/12/2007CGO-20073

4. Yes: Isolation + Communication Many concepts: Domains, processes, messages, channels, contracts, choice, joins, data schema, time, new failure modes This suggests a domain-specific language for “coordination” interoperable across many existing languages No, new features: Forall must be tightly integrated Fewer concepts but interwoven with data abstractions Research: How expensive are safety nets? Transactions should be tightly integrated to support forall Insufficient to handle just at the coordination level 3/12/2007CGO-20074

5. The Few The Many A handfull of experts building highly- scalable widely- leveraged software Performance First. Can exploit HPC prior art in parallel programming Professional Developers somewhere in the middle needing flexibility to be most productive The vast majority that have another job to get done and are opportunistic programmers No surprises: Spend performance to minimize development time/hassle

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7. Microsoft Research Faculty Summit 2007