Memory leaks/slow down when using cvHoughLines2 about javacv HOT 5 CLOSED

You don't need to release it, just clear it with cvClearMemStorage() on every 
iteration 

Can you try to use it in the same way as in the Test2 sample provided in the 
README.txt file?

Thanks for your reply. I already tried creating the memory store only once at 
the start of the program and then calling cvClearMemStorage after each 
iteration (as shown in Test2 from the README.txt file). The behaviour that I 
see is the same as in my memoryLeakExample above. i.e. The time per iteration 
remains constant but the memory taken by the process gradually increases...

I have created a stand alone test that doesn't rely on any external images to 
illustrate this. I would be grateful if you could have a look.

I have also tried checking running it against the latest JavaCV code from the 
SVN and I see the same behaviour. I am using the recommended version of JNA 
(3.2.7). 

Any help would be gratefully received.


import static com.googlecode.javacv.jna.cv.CV_HOUGH_STANDARD;
import static com.googlecode.javacv.jna.cv.cvCanny;
import static com.googlecode.javacv.jna.cv.cvHoughLines2;
import static com.googlecode.javacv.jna.cxcore.cvClearMemStorage;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;

import com.googlecode.javacv.JavaCvErrorCallback;
import com.googlecode.javacv.jna.cxcore.CvMemStorage;
import com.googlecode.javacv.jna.cxcore.CvSeq;
import com.googlecode.javacv.jna.cxcore.IplImage;

public class MemoryTest {

    // class to test creating and releasing images from JavaCV
    public static void main(String[] args) throws IOException,
            InterruptedException {

        new JavaCvErrorCallback().redirectError();

        // create a random image
        IplImage image = createRandomImage();
        IplImage edge = IplImage.create(image.width, image.height, image.depth,
                image.nChannels);
        cvCanny(image, edge, 1000, 1200, 3);
        CvMemStorage storage = CvMemStorage.create();

        long totalTime = 0;

        int iteration = 0;
        while (true) {
            iteration++;

            // carry out the hough lines and store the time taken
            long start = System.currentTimeMillis();
            CvSeq hough = cvHoughLines2(edge, storage.getPointer(),
                    CV_HOUGH_STANDARD, 1, Math.PI / 360, 1000, 20, 40);
            long end = System.currentTimeMillis();
            long time = end - start;
            totalTime += time;
            cvClearMemStorage(storage);

            if (iteration % 1000 == 0) {
                System.out.println(iteration + " mean time per iteration "
                        + (totalTime / 1000));
                System.gc();
                Thread.sleep(500);
                totalTime = 0;
            }

        }

    }

    public static IplImage createRandomImage() {
        int width = 100;
        int height = 100;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_BYTE_GRAY);
        Graphics g = image.getGraphics();
        for (int i = 0; i < 50; i++) {
            int x = (int) (width * Math.random());
            int y = (int) (height * Math.random());
            int x2 = (int) (width * Math.random());
            int y2 = (int) (height * Math.random());
            g.drawLine(x, y, x2, y2);
        }
        return IplImage.createFrom(image);
    }

}

There is a possibility that OpenCV itself is leaking memory.. Have you tried 
something similar in C/C++ to make sure? I get lots of hit on Google search 
about cvHoughLines2 and memory leaks..

I managed to fix the code. I am not sure why this work, but if I called 
cvClearMemStorage on the storage attribute *within* the CvSeq rather than the 
CvMemStorage itself there is no slowdown and no memory leak. To illustrate 
this, in the above example, I simply replaced:

cvClearMemStorage(storage);

with 

cvClearMemStorage(hough.storage);

to solve the problem....

Ah, looks like there is a bug in OpenCV. cvHoughLines2() must ignore the 
storage given as argument and always creates its own. Good to know, thanks for 
reporting