java – ImageIO已同步
作者：互联网
我有一个用户上传图像的Web应用程序.我们通过ImageIO.read()验证图像数据,并在生成的BufferedImage上执行一些简单的转换,然后将其保存到磁盘.
在执行负载测试时,我们意识到当许多请求同时进入时,它们在ImageIO.read()调用中被阻止.深入挖掘,我们注意到JPEGImageReader是同步的,并且一次只创建一个BufferedImage.
还有其他人遇到过这个吗？我已经谷歌搜索了几天,并没有遇到有这个问题的另一个人,所以也许我做错了什么.我无法想出为什么会这样.对于某些内存泄漏问题,似乎无法为每个映像创建单独的读者和写入器,但这种解释对我来说似乎相当薄弱.
编辑：Here是一个性能工具,打破了这么长时间.我相信这是由于所有线程都在等待同步锁,JPEGImageReader源.
编辑：JAI库可以工作,除了OpenJDK已经删除了对它的关键部分的支持,明确地是JPEG编解码器.
解决方案：考虑到我花费大量时间寻找替代解决方案并且未能这样做,我最好的解决方案是根据请求异步处理图像.因此,当请求进入时,原始图像数据被存储为所谓的有效图像;然后,请求线程之外的异步进程将一次处理一个图像.由于ImageIO库的同步性,尝试一次执行多个操作没有任何好处.考虑到库不是同步的,只能是低效的,可以并行处理图像.
虽然异步处理会增加一定程度的复杂性,但在修改图像方面可能是一个好主意.不起作用的是我们无法在每个请求中处理原始图像,这意味着我们的系统必须假设每个图像都是有效的图像数据.当异步处理器确实处理图像时,如果数据不好,可能会出现系统不一致的情况.
解决方法:
While performing load testing, we realized that when many requests come in at the same time, they are being blocked in the ImageIO.read() call. Digging deeper, we noticed that the JPEGImageReader is synchronized and that only one BufferedImage is being created at a time.
Has anyone else come across this?
正如我在评论部分中提到的：从性能分析来看,它看起来像OpenJDK(lcms)的色彩管理系统中的性能问题,因为颜色转换不应该花这么长时间.我的猜测是,无法进一步调试,即使ImageIO能够进行并行解码,这个问题也会使解码(出现)同步.
这是一个SSCCE,显示ImageIO完全能够一次解码多个图像.
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.event.IIOReadProgressListener;
import javax.imageio.stream.ImageInputStream;
import java.io.File;
import java.util.Iterator;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;
class MultipleJPEGDecoding {
private static int threads = Runtime.getRuntime().availableProcessors();
private static ExecutorService executorService = Executors.newFixedThreadPool(threads * 4);
public static void main(final String[] args) throws InterruptedException {
for (int i = 0; i < 100; i++) {
final int index = i;
executorService.submit(new Runnable() {
public void run() {
try {
ImageInputStream stream = ImageIO.createImageInputStream(new File(args[index % args.length]));
try {
Iterator<ImageReader> readers = ImageIO.getImageReaders(stream);
if (!readers.hasNext()) {
System.err.println("No reader!");
return;
}
ImageReader reader = readers.next();
reader.setInput(stream);
reader.addIIOReadProgressListener(new ProgressListener(index));
try {
reader.read(0);
}
finally {
reader.dispose();
}
}
finally {
stream.close();
}
}
catch (Exception e) {
System.err.printf("Error reading %d\n", index);
e.printStackTrace();
}
}
});
}
executorService.shutdown();
}
static class ProgressListener implements IIOReadProgressListener {
final static AtomicInteger simultaneous = new AtomicInteger(0);
final int index;
int nextProgress = 25;
public ProgressListener(int index) {
this.index = index;
}
public void imageStarted(ImageReader source, int imageIndex) {
int inProgress = simultaneous.incrementAndGet();
System.err.printf("Started reading image %d (now decoding %d images simultaneous)...\n", index, inProgress);
}
public void imageComplete(ImageReader source) {
int inProgress = simultaneous.decrementAndGet();
System.err.printf("Done reading image %d%s.\n", index, inProgress > 0 ? String.format(" (still decoding %d other images)", inProgress) : "");
}
public void imageProgress(ImageReader source, float percentageDone) {
if (percentageDone > nextProgress) {
int inProgress = simultaneous.get();
System.err.printf("Progress on image %d (now decoding %d images simultaneous)...\n", index, inProgress);
nextProgress += 25;
}
}
public void sequenceStarted(ImageReader source, int minIndex) {
}
public void sequenceComplete(ImageReader source) {
}
public void thumbnailStarted(ImageReader source, int imageIndex, int thumbnailIndex) {
}
public void thumbnailProgress(ImageReader source, float percentageDone) {
}
public void thumbnailComplete(ImageReader source) {
}
public void readAborted(ImageReader source) {
}
}
}
输出如下：
Started reading image 5 (now decoding 2 images simultaneous)...
Started reading image 0 (now decoding 16 images simultaneous)...
Started reading image 14 (now decoding 15 images simultaneous)...
Started reading image 4 (now decoding 14 images simultaneous)...
Started reading image 13 (now decoding 1 images simultaneous)...
Started reading image 11 (now decoding 13 images simultaneous)...
Started reading image 2 (now decoding 12 images simultaneous)...
Started reading image 15 (now decoding 4 images simultaneous)...
Started reading image 8 (now decoding 11 images simultaneous)...
Started reading image 7 (now decoding 10 images simultaneous)...
Started reading image 9 (now decoding 9 images simultaneous)...
Started reading image 6 (now decoding 8 images simultaneous)...
Started reading image 10 (now decoding 7 images simultaneous)...
Started reading image 1 (now decoding 6 images simultaneous)...
Started reading image 3 (now decoding 5 images simultaneous)...
Started reading image 12 (now decoding 3 images simultaneous)...
Progress on image 11 (now decoding 16 images simultaneous)...
Progress on image 15 (now decoding 16 images simultaneous)...
Progress on image 13 (now decoding 16 images simultaneous)...
Progress on image 13 (now decoding 16 images simultaneous)...
Progress on image 9 (now decoding 16 images simultaneous)...
Progress on image 9 (now decoding 16 images simultaneous)...
Progress on image 1 (now decoding 16 images simultaneous)...
Progress on image 3 (now decoding 16 images simultaneous)...
Progress on image 1 (now decoding 16 images simultaneous)...
Progress on image 3 (now decoding 16 images simultaneous)...
Progress on image 1 (now decoding 16 images simultaneous)...
Progress on image 13 (now decoding 16 images simultaneous)...
Progress on image 5 (now decoding 16 images simultaneous)...
Progress on image 9 (now decoding 16 images simultaneous)...
Progress on image 3 (now decoding 16 images simultaneous)...
Done reading image 3 (still decoding 15 other images).
Started reading image 16 (now decoding 15 images simultaneous)...
Progress on image 11 (now decoding 15 images simultaneous)...
Done reading image 13 (still decoding 14 other images).
Started reading image 17 (now decoding 15 images simultaneous)...
Progress on image 5 (now decoding 15 images simultaneous)...
Progress on image 4 (now decoding 15 images simultaneous)...
Progress on image 11 (now decoding 15 images simultaneous)...
Done reading image 9 (still decoding 14 other images).
Progress on image 5 (now decoding 15 images simultaneous)...
Progress on image 17 (now decoding 15 images simultaneous)...
Done reading image 11 (still decoding 14 other images).
Started reading image 19 (now decoding 15 images simultaneous)...
Progress on image 17 (now decoding 15 images simultaneous)...
Done reading image 5 (still decoding 14 other images).
Started reading image 18 (now decoding 15 images simultaneous)...
Progress on image 15 (now decoding 15 images simultaneous)...
Done reading image 1 (still decoding 14 other images).
Started reading image 21 (now decoding 15 images simultaneous)...
Progress on image 15 (now decoding 15 images simultaneous)...
Progress on image 21 (now decoding 15 images simultaneous)...
Done reading image 15 (still decoding 14 other images).
Progress on image 6 (now decoding 14 images simultaneous)...
Progress on image 21 (now decoding 14 images simultaneous)...
Progress on image 7 (now decoding 14 images simultaneous)...
Progress on image 21 (now decoding 14 images simultaneous)...
Progress on image 7 (now decoding 14 images simultaneous)...
Progress on image 19 (now decoding 14 images simultaneous)...
Progress on image 19 (now decoding 14 images simultaneous)...
Progress on image 7 (now decoding 14 images simultaneous)...
Progress on image 19 (now decoding 14 images simultaneous)...
Done reading image 7 (still decoding 13 other images).
Started reading image 23 (now decoding 14 images simultaneous)...
Progress on image 10 (now decoding 14 images simultaneous)...
Progress on image 23 (now decoding 14 images simultaneous)...
Progress on image 14 (now decoding 14 images simultaneous)...
Started reading image 22 (now decoding 15 images simultaneous)...
Progress on image 0 (now decoding 15 images simultaneous)...
Done reading image 21 (still decoding 14 other images).
Started reading image 24 (now decoding 15 images simultaneous)...
Started reading image 20 (now decoding 16 images simultaneous)...
Progress on image 2 (now decoding 16 images simultaneous)...
Progress on image 8 (now decoding 16 images simultaneous)...
Progress on image 17 (now decoding 15 images simultaneous)...
Done reading image 17 (still decoding 14 other images).
Started reading image 25 (now decoding 15 images simultaneous)...
Progress on image 23 (now decoding 15 images simultaneous)...
Done reading image 19 (still decoding 15 other images).
Started reading image 26 (now decoding 16 images simultaneous)...
Progress on image 23 (now decoding 16 images simultaneous)...
Done reading image 23 (still decoding 15 other images).
Started reading image 27 (now decoding 16 images simultaneous)...
Progress on image 4 (now decoding 16 images simultaneous)...
Progress on image 27 (now decoding 16 images simultaneous)...
Progress on image 27 (now decoding 16 images simultaneous)...
Progress on image 6 (now decoding 16 images simultaneous)...
Progress on image 12 (now decoding 16 images simultaneous)...
Progress on image 20 (now decoding 16 images simultaneous)...
Progress on image 0 (now decoding 16 images simultaneous)...
Progress on image 25 (now decoding 16 images simultaneous)...
Progress on image 25 (now decoding 16 images simultaneous)...
Progress on image 25 (now decoding 16 images simultaneous)...
Progress on image 14 (now decoding 16 images simultaneous)...
Progress on image 10 (now decoding 16 images simultaneous)...
Progress on image 8 (now decoding 16 images simultaneous)...
Progress on image 18 (now decoding 16 images simultaneous)...
Done reading image 25 (still decoding 15 other images).
[…]
Progress on image 75 (now decoding 12 images simultaneous)...
Started reading image 73 (now decoding 13 images simultaneous)...
Progress on image 75 (now decoding 13 images simultaneous)...
Progress on image 73 (now decoding 13 images simultaneous)...
Progress on image 75 (now decoding 13 images simultaneous)...
Started reading image 74 (now decoding 14 images simultaneous)...
Progress on image 66 (now decoding 14 images simultaneous)...
Progress on image 64 (now decoding 14 images simultaneous)...
Progress on image 73 (now decoding 14 images simultaneous)...
Progress on image 60 (now decoding 14 images simultaneous)...
Progress on image 74 (now decoding 14 images simultaneous)...
Progress on image 58 (now decoding 14 images simultaneous)...
Done reading image 75 (still decoding 13 other images).
Progress on image 73 (now decoding 13 images simultaneous)...
Started reading image 77 (now decoding 14 images simultaneous)...
Done reading image 73 (still decoding 13 other images).
Progress on image 77 (now decoding 13 images simultaneous)...
Started reading image 78 (now decoding 14 images simultaneous)...
Progress on image 60 (now decoding 14 images simultaneous)...
Done reading image 48 (still decoding 13 other images).
Progress on image 77 (now decoding 13 images simultaneous)...
Started reading image 79 (now decoding 14 images simultaneous)...
Started reading image 70 (now decoding 15 images simultaneous)...
Progress on image 52 (now decoding 15 images simultaneous)...
Progress on image 71 (now decoding 15 images simultaneous)...
Started reading image 72 (now decoding 16 images simultaneous)...
Progress on image 71 (now decoding 16 images simultaneous)...
Progress on image 54 (now decoding 16 images simultaneous)...
Progress on image 68 (now decoding 16 images simultaneous)...
Progress on image 64 (now decoding 16 images simultaneous)...
Progress on image 66 (now decoding 16 images simultaneous)...
Progress on image 62 (now decoding 16 images simultaneous)...
Progress on image 79 (now decoding 16 images simultaneous)...
Progress on image 79 (now decoding 16 images simultaneous)...
Progress on image 79 (now decoding 16 images simultaneous)...
Progress on image 77 (now decoding 16 images simultaneous)...
Progress on image 68 (now decoding 16 images simultaneous)...
Done reading image 79 (still decoding 15 other images).
Done reading image 77 (still decoding 14 other images).
Started reading image 81 (now decoding 15 images simultaneous)...
Progress on image 74 (now decoding 15 images simultaneous)...
Progress on image 81 (now decoding 15 images simultaneous)...
Progress on image 81 (now decoding 15 images simultaneous)...
Progress on image 78 (now decoding 15 images simultaneous)...
Done reading image 60 (still decoding 14 other images).
Started reading image 82 (now decoding 15 images simultaneous)...
Started reading image 80 (now decoding 16 images simultaneous)...
Progress on image 76 (now decoding 14 images simultaneous)...
Progress on image 66 (now decoding 14 images simultaneous)...
Progress on image 70 (now decoding 14 images simultaneous)...
Done reading image 52 (still decoding 14 other images).
Done reading image 71 (still decoding 15 other images).
Progress on image 81 (now decoding 16 images simultaneous)...
Started reading image 84 (now decoding 15 images simultaneous)...
Started reading image 83 (now decoding 16 images simultaneous)...
Progress on image 58 (now decoding 16 images simultaneous)...
Progress on image 83 (now decoding 16 images simultaneous)...
Progress on image 83 (now decoding 16 images simultaneous)...
Progress on image 83 (now decoding 16 images simultaneous)...
Done reading image 81 (still decoding 15 other images).
Started reading image 85 (now decoding 16 images simultaneous)...
Progress on image 85 (now decoding 16 images simultaneous)...
Progress on image 74 (now decoding 16 images simultaneous)...
Done reading image 66 (still decoding 15 other images).
Started reading image 86 (now decoding 16 images simultaneous)...
Progress on image 64 (now decoding 16 images simultaneous)...
Progress on image 70 (now decoding 16 images simultaneous)...
Progress on image 78 (now decoding 16 images simultaneous)...
Progress on image 54 (now decoding 16 images simultaneous)...
Done reading image 58 (still decoding 15 other images).
Started reading image 87 (now decoding 16 images simultaneous)...
Progress on image 87 (now decoding 16 images simultaneous)...
Progress on image 84 (now decoding 16 images simultaneous)...
Progress on image 87 (now decoding 16 images simultaneous)...
Done reading image 64 (still decoding 15 other images).
Started reading image 88 (now decoding 16 images simultaneous)...
Progress on image 76 (now decoding 16 images simultaneous)...
Done reading image 83 (still decoding 15 other images).
Progress on image 62 (now decoding 15 images simultaneous)...
Progress on image 70 (now decoding 16 images simultaneous)...
Progress on image 85 (now decoding 16 images simultaneous)...
Started reading image 89 (now decoding 16 images simultaneous)...
Progress on image 72 (now decoding 16 images simultaneous)...
Progress on image 85 (now decoding 16 images simultaneous)...
Progress on image 89 (now decoding 16 images simultaneous)...
Done reading image 85 (still decoding 15 other images).
Progress on image 89 (now decoding 15 images simultaneous)...
Progress on image 82 (now decoding 15 images simultaneous)...
Progress on image 80 (now decoding 15 images simultaneous)...
Done reading image 74 (still decoding 14 other images).
Started reading image 91 (now decoding 15 images simultaneous)...
Started reading image 90 (now decoding 16 images simultaneous)...
Done reading image 62 (still decoding 15 other images).
Progress on image 87 (now decoding 15 images simultaneous)...
Progress on image 68 (now decoding 15 images simultaneous)...
Done reading image 87 (still decoding 14 other images).
Progress on image 91 (now decoding 14 images simultaneous)...
Started reading image 93 (now decoding 15 images simultaneous)...
Progress on image 93 (now decoding 15 images simultaneous)...
Progress on image 91 (now decoding 15 images simultaneous)...
Progress on image 91 (now decoding 15 images simultaneous)...
Progress on image 80 (now decoding 15 images simultaneous)...
Started reading image 92 (now decoding 16 images simultaneous)...
Done reading image 91 (still decoding 15 other images).
Started reading image 94 (now decoding 16 images simultaneous)...
Progress on image 93 (now decoding 16 images simultaneous)...
Progress on image 72 (now decoding 16 images simultaneous)...
Progress on image 93 (now decoding 16 images simultaneous)...
Done reading image 93 (still decoding 15 other images).
Started reading image 95 (now decoding 16 images simultaneous)...
Progress on image 95 (now decoding 16 images simultaneous)...
Progress on image 95 (now decoding 16 images simultaneous)...
Progress on image 76 (now decoding 16 images simultaneous)...
Progress on image 95 (now decoding 16 images simultaneous)...
Progress on image 72 (now decoding 16 images simultaneous)...
Done reading image 95 (still decoding 15 other images).
Started reading image 96 (now decoding 16 images simultaneous)...
Progress on image 94 (now decoding 16 images simultaneous)...
Progress on image 89 (now decoding 15 images simultaneous)...
Done reading image 89 (still decoding 14 other images).
Done reading image 54 (still decoding 15 other images).
Started reading image 97 (now decoding 14 images simultaneous)...
Started reading image 98 (now decoding 15 images simultaneous)...
Done reading image 70 (still decoding 13 other images).
Started reading image 99 (now decoding 16 images simultaneous)...
Progress on image 82 (now decoding 16 images simultaneous)...
Progress on image 99 (now decoding 16 images simultaneous)...
Progress on image 99 (now decoding 16 images simultaneous)...
Progress on image 97 (now decoding 16 images simultaneous)...
Progress on image 97 (now decoding 16 images simultaneous)...
Progress on image 97 (now decoding 16 images simultaneous)...
Done reading image 68 (still decoding 15 other images).
Done reading image 97 (still decoding 14 other images).
Progress on image 78 (now decoding 14 images simultaneous)...
Progress on image 99 (now decoding 14 images simultaneous)...
Done reading image 99 (still decoding 13 other images).
Progress on image 86 (now decoding 13 images simultaneous)...
Done reading image 72 (still decoding 12 other images).
Progress on image 82 (now decoding 12 images simultaneous)...
Progress on image 98 (now decoding 12 images simultaneous)...
Progress on image 84 (now decoding 12 images simultaneous)...
Progress on image 90 (now decoding 12 images simultaneous)...
Done reading image 76 (still decoding 11 other images).
Progress on image 92 (now decoding 11 images simultaneous)...
Progress on image 80 (now decoding 11 images simultaneous)...
Progress on image 94 (now decoding 11 images simultaneous)...
Progress on image 88 (now decoding 11 images simultaneous)...
Progress on image 84 (now decoding 11 images simultaneous)...
Progress on image 90 (now decoding 11 images simultaneous)...
Progress on image 92 (now decoding 11 images simultaneous)...
Progress on image 86 (now decoding 11 images simultaneous)...
Progress on image 94 (now decoding 10 images simultaneous)...
Done reading image 84 (still decoding 9 other images).
Progress on image 92 (now decoding 9 images simultaneous)...
Done reading image 78 (still decoding 10 other images).
Progress on image 88 (now decoding 9 images simultaneous)...
Progress on image 90 (now decoding 9 images simultaneous)...
Done reading image 80 (still decoding 8 other images).
Done reading image 82 (still decoding 7 other images).
Progress on image 86 (now decoding 7 images simultaneous)...
Progress on image 96 (now decoding 7 images simultaneous)...
Progress on image 88 (now decoding 7 images simultaneous)...
Done reading image 90 (still decoding 6 other images).
Done reading image 92 (still decoding 5 other images).
Progress on image 98 (now decoding 5 images simultaneous)...
Done reading image 94 (still decoding 4 other images).
Done reading image 86 (still decoding 3 other images).
Progress on image 96 (now decoding 3 images simultaneous)...
Done reading image 88 (still decoding 2 other images).
Progress on image 98 (now decoding 2 images simultaneous)...
Progress on image 96 (now decoding 2 images simultaneous)...
Done reading image 98 (still decoding 1 other images).
Done reading image 96.
标签：java,synchronization,javax-imageio 来源： https://codeday.me/bug/20190517/1121815.html