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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.*;
/** Sorter, performs quicksort on integer arrays
using array partitioning */
public aclass IntSorter returns IntegerArray {
public react(IntegerArray array) {
if (array.size() <= SorterMethods.MIN_PARTITION_SIZE) {
SorterMethods.sortArray(array);
return array;
}
else {
int pivotIndex = SorterMethods.choosePivotIndex(array);
int pivotNewIndex = SorterMethods.partitionArray(array, pivotIndex);
int[] indices = new int[1];
indices[0] = pivotNewIndex;
IntegerArray[] parts = array.split(indices);
IntSorter lhs = new IntSorter();
IntSorter rhs = new IntSorter();
fork ( parts[0] = lhs(parts[0]);
parts[1] = rhs(parts[1]); )
{
array.merge(parts);
return array;
}
}
}
}