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Copyright Tristan Aubrey-Jones May 2008.
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 ./diningTo run examples use:
run ./calc Main run ./dining Main run ./dining Main fast run ./sort Main run ./sort SortingBenchmark
import org.taj.ajava.util.*;
public actor SortingBenchmark implements Entrypoint {
private static final int reptCount = 100;
private IntegerArray arrayA, arrayB, arrayC;
private long Da = 0, Db = 0, Dc = 0;
private IntSorter a;
private IntSorterThread b;
public react(String[] args) {
Stdout <-- "Sorting Benchmark\n";
arrayA = new IntegerArray(10000);
arrayB = new IntegerArray(10000);
arrayC = new IntegerArray(10000);
a = new IntSorter();
b = new IntSorterThread();
this(reptCount);
}
react (int i) {
// seed arrays
SorterMethods.seedArray(arrayA);
SorterMethods.copyArray(arrayA, arrayB);
SorterMethods.copyArray(arrayA, arrayC);
// a test
long T = System.currentTimeMillis();
a(arrayA);
T = System.currentTimeMillis() - T;
Da += T;
// b test
T = System.currentTimeMillis();
b.sort(arrayB);
T = System.currentTimeMillis() - T;
Db += T;
// c test
T = System.currentTimeMillis();
SorterMethods.sortArray(arrayC);
T = System.currentTimeMillis() - T;
Dc += T;
// loop...
if (i > 1) this <-- (i - 1);
else end();
}
void end() {
System.out.print("Actors: ");
System.out.print(Da / reptCount);
System.out.println("ms");
System.out.print("Threads: ");
System.out.print(Db / reptCount);
System.out.println("ms");
System.out.print("Sequential: ");
System.out.print(Dc / reptCount);
System.out.println("ms");
}
}
/*
System.out.println("Sorting Benchmark");
IntegerArray arrayA = new IntegerArray(10000);
IntegerArray arrayB = new IntegerArray(10000);
IntSorter a = new IntSorter();
IntSorterThread b = new IntSorterThread();
int reptCount = 20;
long Ta, Da = 0, Tb, Db = 0;
for (int i = 0; i < reptCount; i++) {
// seed arrays
SorterMethods.seedArray(arrayA);
for (int c = 0; c < arrayA.size(); c++)
arrayB.set(c, arrayA.get(c));
// a test
Ta = System.currentTimeMillis();
a.deliver(IntSorter.Request.create(, 0, array))
Ta = System.currentTimeMillis() - Ta;
Da += Ta;
// b test
Tb = System.currentTimeMillis();
b.sort(arrayB);
Tb = System.currentTimeMillis() - Tb;
Db += Tb;
}
System.out.print("A: ");
System.out.print((double)Da / reptCount);
System.out.println("ms");
System.out.print("B: ");
System.out.print((double)Db/ reptCount);
System.out.println("ms");
*/