Java：为什么/什么是这些线程监视？

我有一个多线程Java应用程序，它将图像分割成4个块，然后4个线程（我有一个四核CPU）分别处理图像的单个块，将其转换为灰度

由于某种原因，我发现它非常慢，所以我使用了NetBeans探查器，发现线程在“监视”（等待）很多。比如说,

（绿色=运行，红色=监控）

我对不同数量的线程进行了实验，例如2个线程，发现这种情况仍然存在（只有1个线程没有出现）

在线程内部，我注释掉了部分代码，直到我将“大延迟”缩小到以下语句：

newImage.setRGB(i,j,newColor.getRGB()); // Write the new value for that pixel

如果将其注释掉，代码运行速度会快很多（几乎是5倍），并且没有线程监控：

那么为什么这一行会造成如此多的延迟呢？是不是颜色库（与BuffereImage一起）？现在，我将尝试获取一个int数组作为RGB值，而不是使用颜色对象，然后看看结果如何

以下是源代码：

PixelsManipulation.java（主类）：

公共最终类像素操作{
私有静态顺序Grayscaler=新顺序（）；
公共静态void main（字符串[]args）抛出FileNotFoundException、IOException、InterruptedException{
File File=新文件（“src/pixelsmanipulation/hiresimage.jpg”）；
FileInputStream fis=新的FileInputStream（文件）；
buffereImage image=ImageIO.read（fis）；//读取图像文件
int rows=2；//2行和2列将图像分割为四分之一
int cols=2；
int chunks=rows*cols；//4个块，图像的每四分之一个块
int chunkWidth=image.getWidth（）/cols；//确定块的宽度和高度
int chunkHeight=image.getHeight（）/行；
整数计数=0；
BuffereImage imgs[]=新BuffereImage[chunks]；//用于保存图像块的数组
对于（intx=0；x

Parallel.java：

// Let each of the 4 threads work on a different quarter of the image
public class Parallel extends Thread{//implements Runnable{

private String threadName;
private static BufferedImage myImage; // Calling it "my" image because each thread will have its own unique quarter of the image to work on
private static int width, height; // Image params

Parallel(String name, BufferedImage image){
    threadName = name;
    System.out.println("Creating "+ threadName);
    myImage = image;
    width = myImage.getWidth();
    height = myImage.getHeight();

}

public void run(){
    System.out.println("Running " + threadName);

    // Pixel by pixel (for our quarter of the image)
    for (int j = 0; j < height; j++){
        for (int i = 0; i < width; i++){

            // Traversing the image and converting the RGB values (doing the same thing as the sequential code but on a smaller scale)
            Color c = new Color(myImage.getRGB(i,j));

            int red = (int)(c.getRed() * 0.299);
            int green = (int)(c.getGreen() * 0.587);
            int blue  = (int)(c.getBlue() * 0.114);

            Color newColor = new Color(red + green + blue, red + green + blue, red + green + blue);

            myImage.setRGB(i,j,newColor.getRGB()); // Write the new value for that pixel


        }
    }

    File output = new File("src/pixelsmanipulation/"+threadName+"grayscale.jpg"); // Put it in a "lower level" folder so we can see it in the project view
    try {
        ImageIO.write(newImage, "jpg", output);
    } catch (IOException ex) {
        Logger.getLogger(Parallel.class.getName()).log(Level.SEVERE, null, ex);
    }
    System.out.println("Thread " + threadName + " exiting. ---");
}
}

//让4个线程中的每一个在图像的不同四分之一上工作
公共类并行扩展线程{//实现可运行{
私有字符串threadName；
private static BufferedImage myImage；//将其称为“我的”映像，因为每个线程都有自己独特的映像四分之一要处理
私有静态整型宽度，高度；//图像参数
并行（字符串名称、缓冲区图像）{
threadName=名称；
System.out.println（“创建”+threadName）；
我的图像=图像；
width=myImage.getWidth（）；
height=myImage.getHeight（）；
}
公开募捐{
System.out.println（“Running”+threadName）；
//逐像素（针对图像的四分之一）
对于（int j=0；j

我是Java线程（以及使用BuffereImage）的初学者，只是好奇

// Let each of the 4 threads work on a different quarter of the image
public class Parallel extends Thread{//implements Runnable{

private String threadName;
private static BufferedImage myImage; // Calling it "my" image because each thread will have its own unique quarter of the image to work on
private static int width, height; // Image params

Parallel(String name, BufferedImage image){
    threadName = name;
    System.out.println("Creating "+ threadName);
    myImage = image;
    width = myImage.getWidth();
    height = myImage.getHeight();

}

public void run(){
    System.out.println("Running " + threadName);

    // Pixel by pixel (for our quarter of the image)
    for (int j = 0; j < height; j++){
        for (int i = 0; i < width; i++){

            // Traversing the image and converting the RGB values (doing the same thing as the sequential code but on a smaller scale)
            Color c = new Color(myImage.getRGB(i,j));

            int red = (int)(c.getRed() * 0.299);
            int green = (int)(c.getGreen() * 0.587);
            int blue  = (int)(c.getBlue() * 0.114);

            Color newColor = new Color(red + green + blue, red + green + blue, red + green + blue);

            myImage.setRGB(i,j,newColor.getRGB()); // Write the new value for that pixel


        }
    }

    File output = new File("src/pixelsmanipulation/"+threadName+"grayscale.jpg"); // Put it in a "lower level" folder so we can see it in the project view
    try {
        ImageIO.write(newImage, "jpg", output);
    } catch (IOException ex) {
        Logger.getLogger(Parallel.class.getName()).log(Level.SEVERE, null, ex);
    }
    System.out.println("Thread " + threadName + " exiting. ---");
}
}