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'''Multi-Thread Program in Java'''
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.ArrayList;
public class Java_Thread {
public List<ArrayList<ArrayList<Integer>>> read(String filename) {
ArrayList<ArrayList<Integer>> A = new ArrayList<ArrayList<Integer>>();
ArrayList<ArrayList<Integer>> B = new ArrayList<ArrayList<Integer>>();
String thisLine;
try {
BufferedReader br = new BufferedReader(new FileReader(filename));
while ((thisLine = br.readLine()) != null) {
if (thisLine.trim().equals("")) {
break;
} else {
ArrayList<Integer> line = new ArrayList<Integer>();
String[] lineArray = thisLine.split("\t"); for (String number : lineArray) {
line.add(Integer.parseInt(number));
}
A.add(line);
}
}
while ((thisLine = br.readLine()) != null) {
ArrayList<Integer> line = new ArrayList<Integer>();
String[] lineArray = thisLine.split("\t");
for (String number : lineArray) {
line.add(Integer.parseInt(number));
}
B.add(line);
}
br.close();
} catch (IOException e) {
System.err.println("Error: " + e);
}
List<ArrayList<ArrayList<Integer>>> res = new LinkedList<ArrayList<ArrayList<Integer>>>();
res.add(A);
res.add(B);
return res;
}
public int[][] matrixMultiplication(ArrayList<ArrayList<Integer>> A, ArrayList<ArrayList<Integer>> B, int m, int n) {
int[][] C = new int[m][n];
for (int i = 0; i < m; i++) {
for (int k = 0; k < n; k++) {
int temp = A.get(i).get(k);
for (int j = 0; j < n; j++) {
C[i][j] += temp * B.get(k).get(j);
}
}
}
return C;
}
public ArrayList<ArrayList<ArrayList<Integer>>> splitMatrix(ArrayList<ArrayList<Integer>> A, int nrOfThreads) {
int n = A.size();
int m = n / nrOfThreads;
ArrayList<ArrayList<ArrayList<Integer>>> B = new
ArrayList<ArrayList<ArrayList<Integer>>>();
for (int i = 0; i < nrOfThreads; i++){
B.add(new ArrayList<ArrayList<Integer>>(A.subList(i*m, (i+1)*m)));
}
return B;
}
public static void main(String[] args) {
String filename = "";
int nrOfThreads = 0;
if (args.length < 2) {
System.out.println("Missing filename and/or number of threads\nUSAGE: java Java_Thread <file> <nrOfThreads>");
System.exit(1);
} else {
filename = args[0];
nrOfThreads = Integer.parseInt(args[1]);
Java_Thread java_Thread = new Java_Thread();
java_Thread.start(filename, nrOfThreads);
}
}
public void start(String filename, int nrOfThreads) {
List<ArrayList<ArrayList<Integer>>> matrices = read(filename);
ArrayList<ArrayList<Integer>> A = matrices.get(0);
ArrayList<ArrayList<Integer>> B = matrices.get(1);
if (nrOfThreads <= 0) {
int n = A.size();
long startTime = System.nanoTime();
int[][] C = matrixMultiplication(A, B, n, n);
long endTime = System.nanoTime();
System.out.println("Execution took " + (endTime - startTime) + " ns");
} else {
if (A.size() % nrOfThreads != 0) {
System.out.println("Size of matrix is not divisible by the supplied number of threads");
System.exit(1);
}
ArrayList<Worker> threads = new ArrayList<Worker>();
ArrayList<int[][]> result = new ArrayList<int[][]>();
int[][] empty = new int[][]{{}};
for (int i = 0; i < nrOfThreads; i++) {
result.add(empty);
}
ArrayList<ArrayList<ArrayList<Integer>>> workerMatrices = splitMatrix(A, nrOfThreads);
long startTime = System.nanoTime();
for (int i = 0; i < nrOfThreads; i++) {
i, result));
}
threads.add(new Worker(workerMatrices.get(i), B, threads.get(i).start();
for (int i = 0; i < nrOfThreads; i++) {
try {
threads.get(i).join();
} catch (Exception e) {
System.err.println(e);
}
}
long endTime = System.nanoTime();
System.out.println("Execution took " + (endTime - startTime) + " ns");
}
}
class Worker extends Thread {
private ArrayList<ArrayList<Integer>> A;
private ArrayList<ArrayList<Integer>> B; private int index;
private ArrayList<int[][]> result; private int m;
private int n;
public Worker(ArrayList<ArrayList<Integer>> A, ArrayList<ArrayList<Integer>> B, int index, ArrayList<int[][]> result) {
this.A = A;
this.B = B;
this.index = index;
this.result = result;
this.m = A.size();
this.n = B.size();
}
@Override
public void run() {
this.result.set(this.index, matrixMultiplication(this.A, this.B, this.m, this.n));
}
}
}
===Result===