Run‐time optimizations for a Java DSM implementation

Abstract

AbstractJackal is a fine‐grained distributed shared memory implementation of the Java programming language. Jackal implements Java's memory model and allows multithreaded Java programs to run unmodified on distributed‐memory systems.This paper focuses on Jackal's run‐time system, which implements a multiple‐writer, home‐based consistency protocol. Protocol actions are triggered by software access checks that Jackal's compiler inserts before object and array references. To reduce access‐check overhead, the compiler exploits source‐level information and performs extensive static analysis to optimize, lift, and remove access checks. We describe optimizations for Jackal's run‐time system, which mainly consists of discovering opportunities to dispense with flushing of cached data. We give performance results for different run‐time optimizations, and compare their impact with the impact of one compiler optimization. We find that our run‐time optimizations are necessary for good Jackal performance, but only in conjunction with the Jackal compiler optimizations described by Veldema et al. As a yardstick, we compare the performance of Java applications run on Jackal with the performance of equivalent applications that use a fast implementation of Java's Remote Method Invocation instead of shared memory. Copyright © 2003 John Wiley & Sons, Ltd.