Expressing and exploiting concurrency in networked applications with aspen

Abstract

This paper presents Aspen, a high-level programming language thattargets both high-productivity programming and runtime support formanaging resources needed by a computation. Programs in Aspen arerepresented as directed graphs, where the edges are well-definedunidirectional communication channels and the nodes are instances of computational modules that process the incoming data. The resulting representation of a program closely resembles a flow chart describing the flow of computation in a server application and exposing the communicationat a high level of abstraction. This strategy for program composition naturally allows parallelism and data sharing to be factored out of the core computational logic of a program, facilitating a division of labor between parallelism expertsand application experts and also easing code development and maintenance. Aspen automatically and transparently supports task-level parallelism among module instancesand data-level parallelism across different flows in an application or, in some cases, across different work items within a flow. Aspen automatically and adaptively allocates threads to modules according to the dynamic workload seen at those modules.