[SOLVED] How to close a physics space to free up ram

sgold · November 12, 2024, 6:36pm

I’m actually not sure what setLocalThreadPhysicsSpace() does

Here’s the source code:

stephengold/Minie/blob/917969ecf1027cecc7ea8520b21c48ff33477c8c/MinieLibrary/src/main/java/com/jme3/bullet/CollisionSpace.java#L114-L123


      
          /**
           * collision-space reference for each thread
           * <p>
           * When a collision space is created, the current thread automatically
           * becomes associated with it. For the space to be garbage collected, the
           * same thread should null out its reference (using
           * {@code setLocalThreadPhysicsSpace()}) before terminating.
           */
          final private static ThreadLocal<CollisionSpace> physicsSpaceTL
                  = new ThreadLocal<>();

github.com

stephengold/Minie/blob/917969ecf1027cecc7ea8520b21c48ff33477c8c/MinieLibrary/src/main/java/com/jme3/bullet/CollisionSpace.java#L733-L741


      
          /**
           * Alter the CollisionSpace associated with this thread.
           *
           * @param space which space to associate with the current thread, or
           * {@code null} for none
           */
          public static void setLocalThreadPhysicsSpace(CollisionSpace space) {
              physicsSpaceTL.set(space);
          }

I assume the original idea was to support server-side applications that simulate multiple physics spaces in parallel, each space having its own thread.

When a space is created, a strong reference is stored in thread-local data. The JVM can’t reclaim the space until the reference is cleared.