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Automatically Exploiting Implicit Parallelism in Java

Aart J.C. Bik and Dennis B. Gannon
Lindley Hall 215, Computer Science Dept., Indiana University
Bloomington, Indiana 47405-4101, USA


In this paper we show how implicit parallelism in Java programs can be made explicit by a restructuring compiler using the multi-threading mechanism of the language. In particular, we focus on automatically exploiting implicit parallelism in loops and multi-way recursive methods. Expressing parallelism in Java itself clearly has the advantage that the transformed program remains portable. After compilation of the transformed Java program into bytecode, speedup can be obtained on any platform on which the Java bytecode interpreter supports the true parallel execution of threads. Moreover, we will see that the transformations presented in this paper only induce a slight overhead on uni-processors.