java - 使用线程池将双数组(矩阵)添加在一起

Question

我想使用线程池将两个矩阵相互添加，这将导致进程更快地完成。当我不使用执行器框架进行添加时，程序运行良好，但当我实现线程池时，程序崩溃了。问题必须出在添加方法中，任何帮助使其运行的帮助都会有所帮助!谢谢:)。

这是矩阵类的代码。我没有包含主类，因为它所做的只是获取创建矩阵的维度。如果您还想要主类，请告诉我，我会将其包含在内。

package matrixproject;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Matrix {
    int row;
    int column;

    int [][] matrixArray;

    public Matrix(){    
    }
    public Matrix (int numberofRows,int numberofColumns,int maxNumber,int minNumber){

        this.row = numberofRows;
        this.column = numberofColumns;

        matrixArray = new int [row][column];

        populateMatrix(minNumber,maxNumber);

    }
    public Matrix(int [][] matrixArrayCopy)
   {
       this.row = matrixArrayCopy.length;
       this.column = (matrixArrayCopy[0]).length;

       matrixArray = new int[row][column];

       for(int i=0; i<row; i++)
       {
           System.arraycopy(matrixArrayCopy[i], 0, matrixArray[i], 0, column);
       }
   }
     private void populateMatrix(int min, int max)
   {
       Random rand = new Random();

       for (int i=0; i<row; i++)
       {
           for (int j=0; j<column; j++)
           {
               matrixArray[i][j] = rand.nextInt((max - min) + 1) + min;
           }
       }
   }
    public Matrix addition (Matrix additionMatrix){
        int threadnum = Runtime.getRuntime().availableProcessors();
        ExecutorService executor = Executors.newFixedThreadPool(threadnum);
        int [][] matrixAddResult = new int [this.row][this.column]; 
        for (int i = 0; i <row; i+=1){
            for (int j =0; j <column; j+=1){
                //made new variables equal to i and j to get around needing a final variable for the lambda function 
                int index = i;
                int jndex = j;

                executor.submit(() -> {
                matrixAddResult[index][jndex] += this.matrixArray[index][jndex] + additionMatrix.matrixArray[index][jndex];

          });
            executor.shutdown();
            }
        }
        return new Matrix(matrixAddResult);
    }

以下是我在使用添加方法时遇到的错误:

Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task java.util.concurrent.FutureTask@452b3a41 rejected from java.util.concurrent.ThreadPoolExecutor@4a574795[Shutting down, pool size = 1, active threads = 1, queued tasks = 0, completed tasks = 0]
    at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2047)
    at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:823)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1369)
    at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112)
    at matrixproject.Matrix.addition(Matrix.java:65)
    at matrixproject.MatrixProject.main(MatrixProject.java:73)
Java Result: 1

Answer 1

它的字面意思是:在异常中“关闭”。 :)

您在内循环中调用 shutdown() 方法，这意味着您尝试在池已经收到关闭命令后的下一次迭代中提交新任务，这就是为什么您收到拒绝异常(exception)情况。

将 executor.shutdown(); 移到顶级 for 循环之外