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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
public aclass ALU {
private double register;
private char operator = '=';
public final Event OnResult = new Event();
public ALU() {
register = 0.0;
}
// perform operation
public react (Calculator.Operation op) {
System.out.print(op.operand);
System.out.print(op.operator);
// perform op
switch (operator) {
case '+': register += op.operand; break;
case '-': register -= op.operand; break;
case '*': register *= op.operand; break;
case '/': register /= op.operand; break;
case '^': register = Math.pow(register, op.operand); break;
// if was equals then new reg is operand
case '=': register = op.operand; break;
}
operator = op.operator;
// raise event
System.out.println(" returns " + Double.toString(register));
OnResult <-- register;
}
}