ActiveJava

Abstract: A project investigating and developing an implicitly concurrent programming language, based on a metaphor taken from the physical world is reported. Uses a programming paradigm where programs consist of systems of autonomous agents, or active objects which communicate via message passing. A language enhancing Java with actors and linear types is presented. Example programs are written, compiled, and executed to evaluate the usefulness of the language. The language found to provide a familiar notation for implicit parallelism, and a compelling new model for concurrency, combining the performance of shared variables with the elegance of message passing.

Introductory Slides (PDF), Report (PDF),
ActiveJava compiler prototype (ajavac), ActiveJava runtime library (ajava_lang).

Examples:

calc - pocket calculator actor program
dining - dining philosophers actor program (never deadlocks)
sort - parallel quicksort implementation ("SortBenchmark" sorts 10,000 random integers using actors, java threads, and sequentially and compares)

To compile examples use:

compile.bat ./calc
compile.bat ./sort
compile.bat ./dining

To run examples use:

run ./calc Main
run ./dining Main
run ./dining Main fast
run ./sort Main
run ./sort SortingBenchmark

ListIterator.ajava

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import java.util.List;  

/** list iterator iterates over all 
  * values in the list when receives run
  * to use extend from this and override
  * reaction to Object, which is called 
  * for every iteration. */
public aclass ListIterator {
    private List list;

    public ListIterator(List list) {
        this.list = list;
    }

    public static class Run {}
    public react(Run r) { 
        if (list.size() > 0) this(list.size()-1); 
    }

    public react(Object v) {}

    private react(int it) {
        this(list.get(it));
        if (it > 0) this <-- it - 1;
    }
}