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

Main.ajava

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import org.taj.ajava.util.*;

public actor Main implements Entrypoint {

    public react(String[] args) {
        // say hello
        if (args.length > 0) Stdout <-- "Hello " + args[0] + "!";
        else Stdout <-- "Hello World!";
        
        // generate an array of integers
        IntegerArray array = new IntegerArray(10000);
        SorterMethods.seedArray(array);
        
        // start timer
        long t = System.currentTimeMillis();
        
        // quick-sort an array of integers
        IntSorter sorter = new IntSorter();
        array = sorter(array);
        //IntSorterThread sorter = new IntSorterThread();
        //array = sorter.sort(array);
        
        // stop timer
        t = System.currentTimeMillis() - t;
        Stdout <-- Long.toString(t);
        
        SorterMethods.printArray(array);
    }
    
}