我正在寫一個小的Java應用程序來分析大量的圖像文件。目前,它通過平均圖像中每個像素的亮度並將其與文件夾中的其他圖像進行比較來找到文件夾中最亮的圖像。爲什麼啓動後我的Java程序的性能顯着下降?
有時候,啓動後我會得到100張圖像/秒的速度,但是這幾乎總是會下降到每秒20張圖像的<,我不知道爲什麼。如果速度爲每秒100張以上,則CPU使用率爲100%,但會降至20%左右,看起來太低。
這裏的主類:
public class ImageAnalysis {
public static final ConcurrentLinkedQueue<File> queue = new ConcurrentLinkedQueue<>();
private static final ConcurrentLinkedQueue<ImageResult> results = new ConcurrentLinkedQueue<>();
private static int size;
private static AtomicInteger running = new AtomicInteger();
private static AtomicInteger completed = new AtomicInteger();
private static long lastPrint = 0;
private static int completedAtLastPrint;
public static void main(String[] args){
File rio = new File(IO.CAPTURES_DIRECTORY.getAbsolutePath() + File.separator + "Rio de Janeiro");
String month = "12";
Collections.addAll(queue, rio.listFiles((dir, name) -> {
return (name.substring(0, 2).equals(month));
}));
size = queue.size();
ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() + 1);
for (int i = 0; i < 8; i++){
AnalysisThread t = new AnalysisThread();
t.setPriority(Thread.MAX_PRIORITY);
executor.execute(t);
running.incrementAndGet();
}
}
public synchronized static void finished(){
if (running.decrementAndGet() <= 0){
ImageResult max = new ImageResult(null, 0);
for (ImageResult r : results){
if (r.averageBrightness > max.averageBrightness){
max = r;
}
}
System.out.println("Max Red: " + max.averageBrightness + " File: " + max.file.getAbsolutePath());
}
}
public synchronized static void finishedImage(ImageResult result){
results.add(result);
int c = completed.incrementAndGet();
if (System.currentTimeMillis() - lastPrint > 10000){
System.out.println("Completed: " + c + "/" + size + " = " + ((double) c/(double) size) * 100 + "%");
System.out.println("Rate: " + ((double) c - (double) completedAtLastPrint)/10D + " images/sec");
completedAtLastPrint = c;
lastPrint = System.currentTimeMillis();
}
}
}
和線程類:
public class AnalysisThread extends Thread {
@Override
public void run() {
while(!ImageAnalysis.queue.isEmpty()) {
File f = ImageAnalysis.queue.poll();
BufferedImage image;
try {
image = ImageIO.read(f);
double color = 0;
for (int x = 0; x < image.getWidth(); x++) {
for (int y = 0; y < image.getHeight(); y++) {
//Color c = new Color(image.getRGB(x, y));
color += image.getRGB(x,y);
}
}
color /= (image.getWidth() * image.getHeight());
ImageAnalysis.finishedImage((new ImageResult(f, color)));
} catch (IOException e) {
e.printStackTrace();
}
}
ImageAnalysis.finished();
}
}
您可以使用jvisualvm等分析器運行您的應用程序,並使用其採樣器來測量哪種方法最耗時。另外,嘗試在單個線程中運行它並觀察任何差異。線程可能在某些操作上互相阻塞。 –
你的類擴展了'Thread',並且你正在設置它的優先級,但是你通過'Executor'來運行它,它只把它看作是'Runnable',所以這一切都是徒勞的。如果你想影響優先級,你需要定義一個'ThreadFactory.',否則你的類可能只是實現Runnable。 – EJP
你有沒有試過:'ImageIO.setUseCache(false);'? – user3707125