fix: make PyObject cleanup thread-safe in free-threaded Python and re…

…duce contention (#176)

* Fix a bug in Py Obj cleanup & reduce contention

* Remove unneeded code

* enable the java-to-python tests

* Revert "enable the java-to-python tests"

This reverts commit 5de1fe2.

src/main/java/org/jpy/PyObject.java

@@ -42,8 +42,6 @@ public class PyObject implements AutoCloseable {
 
     private static final AtomicReference<Thread> CLEANUP_THREAD = new AtomicReference<>();
 
-    private static final boolean CLEANUP_ON_INIT = Boolean.parseBoolean(System.getProperty("PyObject.cleanup_on_init", "true"));
-
     private static final boolean CLEANUP_ON_THREAD = Boolean.parseBoolean(System.getProperty("PyObject.cleanup_on_thread", "true"));
 
     private static void startCleanupThread() {
@@ -71,9 +69,6 @@ public static int cleanup() {
     PyObject(long pointer, boolean fromJNI) {
         state = new PyObjectState(pointer);
         if (fromJNI) {
-            if (CLEANUP_ON_INIT) {
-                REFERENCES.threadSafeCleanup(); // only performs *one* cleanup
-            }
             if (CLEANUP_ON_THREAD) {
                 // ensures that we've only started after python has been started, and we know there is something to cleanup
                 startCleanupThread();

src/main/java/org/jpy/PyObjectReferences.java

@@ -76,11 +76,7 @@ private Reference<PyObject> asRef(PyObject pyObject) {
     /**
      * This should *only* be invoked through the proxy, or when we *know* we have the GIL.
      */
-    public int threadSafeCleanup() {
-        return threadSafeCleanup(buffer);
-    }
-
-    private int threadSafeCleanup(long[] buffer) {
+    public synchronized int threadSafeCleanup() {
         return PyLib.ensureGil(() -> {
             int index = 0;
             while (index < buffer.length) {