How to clear the cloned frame correctly？

[4714407]

When I use the clone method on frame, I find that the memory has been increasing and has not been released. I see that the comment of the method says:"Expect a heap overflow exception when using this method without cleaning up."
Can you tell me how to clear the frame object correctly?
I would like to ask, in addition to passive garbage collection, is there any way to manually free memory?

[saudet]

The underlying methods use Pointer to allocate memory, so we can use PointerScope in the fashion introduced here:
http://bytedeco.org/news/2018/07/17/bytedeco-as-distribution/

[saudet]

Ideally though it should probably implement AutoCloseable to let us deallocate manually in such instances.

[saudet]

However, that's going to require adding reference counting for pointers in other areas of FrameConverter, FrameGrabber, FrameFilter, and FrameRecording, so let's add that to the "to-do list".

[4714407]

Thank you for your reply.

The frame I cloned is passed to the child thread for use, so what if I use this PointerScope

[saudet]

That's fine, you can pass the PointerScope to the thread as well, possibly after calling PointerScope.extend().

[4714407]

Can you give me a sample code? I'm sorry, I still don't know how to use it

[saudet]

There's some more sample code in the unit tests here:
https://github.com/bytedeco/javacpp/blob/master/src/test/java/org/bytedeco/javacpp/PointerTest.java#L958

[4714407]

Please help to see if the following code is correct?

while ((frame = grabber.grabImage()) != null) {
   if (frame.image != null) {
        try (PointerScope scope = new PointerScope()) {
                            final Frame finalFrame = frame.clone();
                            final PointerScope extendedLocalScope = scope.extend();
                            new Thread(new Runnable() {
                                @Override
                                public void run() {
                                    Java2DFrameConverter java2dFrameConverter = new Java2DFrameConverter();
                                    BufferedImage bufferedImage = java2dFrameConverter.convert(finalFrame);
                                    //do something
                                    extendedLocalScope.close();
                                }
                            }).start();
                        }
   }
}

[saudet]

Yes, that should work... But if you have a lot of those frames, you should create single instances of everything and reuse them.

[4714407]

It works. Thank you very much!

[saudet]

The Frame class in JavaCV 1.5.5 now comes with a close() method for that purpose. Enjoy and thanks for reporting!