Isolation for nested task parallelism

Abstract

Isolation--the property that a task can access shared data without interference from other tasks--is one of the most basic concerns in parallel programming. Whilethere is a large body of past work on isolated task-parallelism, the integration of isolation, task-parallelism, and nesting of tasks has been a difficult and unresolved challenge. In this pa- per, we present a programming and execution model called Otello where isolation is extended to arbitrarily nested parallel tasks with irregular accesses to heap data. At the same time, no additional burden is imposed on the programmer, who only exposes parallelism by creating and synchronizing parallel tasks, leaving the job of ensuring isolation to the underlying compiler and runtime system.