BufferedImage.createGraphics（）内存泄漏

Question

The code below produces a memory leak.

public static BufferedImage mergeImages2(BufferedImage base, Collection<Light> images) {
    BufferedImage output = new BufferedImage(base.getWidth(), base.getHeight(), BufferedImage.TYPE_INT_ARGB);

    Graphics2D g = output.createGraphics();
    g.drawImage(base, 0, 0, null);
    g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_IN, 1.0f));
    for (Light l : images) {
        g.drawImage(l.LIGHT_IMAGE, l.x, l.y, null);
        l.LIGHT_IMAGE.flush();
    }
    g.dispose();
    output.flush();
    return output;
}

As I have read here: BufferedImage.getGraphics() resulting in memory leak, is there a fix? .createGraphics() is the problem.

This code can be executed quite often (a timer is set up to tick at a constant rate of 50ms and if a light is "moving" it calls this code, but if lights stay in the same place this is skipped). It runs fine but everytime makes the process clunk memory, which is a cascade process eventually leading to an increase from ~180 000 K memory to more than 600 000 K memory in less then one minute. Graphically it works fine until at some point the clunk becomes too much (obviously) and FPS drop drastically.

Now I have narrowed down that this block produces the leak as commenting its call out makes the problem go away.

The base image drawn is 1024x561 and the lights' images are rather small (50x50). I have always been testing it with only one light in the array so far.

Any solutions to avoiding the memory leak?

Answer 1

As Andrew Thompson commented, this is not necessarily a memory leak. The garbage collector might simply start later than you think. You could try experimenting with a System.gc() call, when the lights are not moving, although generally calling System.gc() is not recommended: When does System.gc() do anything

Alternatively you could try to manipulate directly the integer arrays that are behind your BufferedImage (not easy), or perhaps to use another API (like JOGL).