Posted by gouessej on Mar 01, 2023; 9:18am
URL: https://forum.jogamp.org/Freeing-a-direct-NIO-buffer-with-CLinker-freeMemory-causes-a-double-free-or-corruption-tp4042228p4042250.html

Hello Sven

Sorry, the documentation of this method is here:
https://docs.oracle.com/en/java/javase/17/docs/api/jdk.incubator.foreign/jdk/incubator/foreign/CLinker.html#freeMemory(jdk.incubator.foreign.MemoryAddress)

I used this method to free the allocated memory of a direct NIO buffer in a more straightforward manner than by relying on non public fields and methods. The use case is quite common in games, there are some appropriate moments to determine whether you still need some resources and when they are no longer useful (when you leave a level), you don't want to keep them, which isn't a problem when you deal only with the Java heap most of the time (the garbage collector G1 works well and you can use a Low-Pause-Time garbage collector like Shenandoah) but it's trickier when you deal with the native heap. I have used for years some very complicated source code to clean the mess. The method above was intended to allow to clean this mess a lot more easily by allowing to wrap a direct NIO buffer into some objects of a more recent API only when you need to free the native memory. However, it wasn't working correctly.

When I use Java 19, I have to use java.lang.foreign to create the direct NIO buffer, not only to destroy them. It requires much more changes. I'll probably have to add a flexible mechanism into JogAmp's Ardor3D Continuation to allow to override the build-in helper that creates the direct NIO buffer. I don't want to add a strong dependency to a preview API into the core of the engine.