Abstract: A service request is processed according to a computation graph associated with the service by receiving inputs for the computation graph from a service client, providing the inputs to the computation graph as records of a data flow, receiving output from the computation graph, and providing the output to the service client. Data flows are processed concurrently in a graph-based computation by potentially concurrent execution of different types of requests, potentially concurrent execution of similar request types, and/or potentially concurrent execution of work elements within a request.