Home
Up
(
Download )
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 java.util.*;
import org.taj.ajava.lang.*;
public class Clock {
private long T = 0;
private long period;
private ArrayList actorList = new ArrayList();
private Timer timer;
private TimerTask task;
public Clock(long period) {
this.period = period;
timer = new Timer();
task = new Task();
}
public class Tick {
public long value;
public Tick(long value) {
this.value = value;
}
}
public void subscribe(Actor a) {
this.actorList.add(a);
}
public void unsubscribe(Actor a) {
this.actorList.remove(a);
}
private void sendToAll(){
for (Object o: actorList) {
Tick t = new Tick(T);
Actor.sendMessage((Actor)o, t);
}
}
private class Task extends TimerTask {
public void run() {
T++;
sendToAll();
}
}
public void start() {
timer.scheduleAtFixedRate(task, 0, period);
}
public void stop() {
task.cancel();
}
}