通过使用CyclicBarrier来计算Matrix中最大的值

import java.util.Random;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Created by ltao on 2015/1/14.
 * 通过使用CyclicBarrier来计算Matrix中最大的值
 */

class FindMax {
    public static void findMax(int rowStart, int rowEnd, int[] maxs, int[][] matrix, int length) {
        for (int i = rowStart; i < rowEnd; i++) {
            int[] tmp = matrix[rowStart];
            int max = -1;
            for (int j = 0; j < length; j++) {
                if (max < tmp[j]) {
                    max = tmp[j];
                }
            }
            maxs[i] = max;
        }
    }
}

class SubMatrix implements Runnable {
    private int rowStart;
    private int rowEnd;
    int[] maxs;
    int[][] matrix;
    int length;

    private CyclicBarrier cyclicBarrier;

    public SubMatrix(int rowStart, int rowEnd, int[] maxs, int[][] matrix, int length, CyclicBarrier cyclicBarrier) {
        this.rowStart = rowStart;
        this.rowEnd = rowEnd;
        this.maxs = maxs;
        this.matrix = matrix;
        this.length = length;
        this.cyclicBarrier = cyclicBarrier;
    }

    public int getRowStart() {
        return rowStart;
    }

    public void setRowStart(int rowStart) {
        this.rowStart = rowStart;
    }

    public int getRowEnd() {
        return rowEnd;
    }

    public void setRowEnd(int rowEnd) {
        this.rowEnd = rowEnd;
    }

    public int[] getMaxs() {
        return maxs;
    }

    public void setMaxs(int[] maxs) {
        this.maxs = maxs;
    }

    public int[][] getMatrix() {
        return matrix;
    }

    public void setMatrix(int[][] matrix) {
        this.matrix = matrix;
    }

    public int getLength() {
        return length;
    }

    public void setLength(int length) {
        this.length = length;
    }

    @Override
    public void run() {
        try {
            FindMax.findMax(rowStart, rowEnd, maxs, matrix, length);
            this.cyclicBarrier.await();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

public class MatrixCounter {

    public static void main(String[] args) {

        final int row = 100000;
        int length = 2000;
        final int[][] matrix = new int[row][length];
        Random random = new Random();
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < length; j++) {
                matrix[i][j] = random.nextInt(3000);
            }
        }



        final int[] maxs = new int[row];
        int coreSize = Runtime.getRuntime().availableProcessors();
        int threadNum = coreSize;

        if (row < coreSize) {
            threadNum = row;
        }


        CyclicBarrier cyclicBarrier = new CyclicBarrier(threadNum, new Runnable() {
            @Override
            public void run() {
                int max = -1;
                for (int i = 0; i < row; i++) {
                    if (maxs[i] > max) {
                        max = maxs[i];
                    }
                }
                System.out.println("max:" + max);
            }
        });
        System.out.println("线程数目:"+threadNum);
        ExecutorService executor = Executors.newFixedThreadPool(threadNum);
        for (int i = 0; i < threadNum; i++) {
            int rowSart = i * (row / threadNum);
            int rowEnd = 0;
            if (i != threadNum - 1) {
                rowEnd = (i + 1) * (row / threadNum) - 1;
            } else {
                rowEnd = row - 1;
            }
            executor.execute(new SubMatrix(rowSart, rowEnd, maxs, matrix, length, cyclicBarrier));
        }


    }


}