Cleanup Java mirror of thread state pointer for thread disposal in PyGILState_Release

Author: steve-s

graalpython/com.oracle.graal.python.cext/src/pystate.c

@@ -177,6 +177,12 @@ PyGILState_Release(PyGILState_STATE oldstate)
 {
     if (oldstate == PyGILState_UNLOCKED) {
         GraalPyTruffleGILState_Release();
+        /* In the GraalPyTruffleGILState_Release up-call, we cleaned-up the pointer saved in
+         * Java level Python thread state to avoid setting it to NULL in Truffle thread disposal
+         * code, because it is not clear if the native thread is guaranteed to still be around
+         * when the Truffle thread is being disposed.
+         */
+        tstate_current = NULL;
     }
     if (TRUFFLE_CONTEXT) {
         graalpy_gilstate_counter--;

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/cext/PythonCextPyStateBuiltins.java

@@ -50,6 +50,7 @@
 import static com.oracle.graal.python.builtins.objects.cext.capi.transitions.ArgDescriptor.Py_ssize_t;
 import static com.oracle.graal.python.builtins.objects.cext.capi.transitions.ArgDescriptor.Void;
 
+import com.oracle.graal.python.PythonLanguage;
 import com.oracle.graal.python.builtins.modules.cext.PythonCextBuiltins.CApiBuiltin;
 import com.oracle.graal.python.builtins.modules.cext.PythonCextBuiltins.CApiNullaryBuiltinNode;
 import com.oracle.graal.python.builtins.modules.cext.PythonCextBuiltins.CApiUnaryBuiltinNode;
@@ -102,6 +103,10 @@ abstract static class PyTruffleGILState_Release extends CApiNullaryBuiltinNode {
         static Object restore(
                         @Cached GilNode gil) {
             gil.release(true);
+            // The C API that makes this up-call should reset the thread local variable to NULL
+            // and here, on the Java side, we can clean up the pointers, because there is no need
+            // to reset the native thread local on Truffle thread disposal
+            getContext(gil).getThreadState(PythonLanguage.get(gil)).resetNativeThreadLocalVarPointer();
             return PNone.NO_VALUE;
         }
     }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonContext.java

@@ -636,6 +636,11 @@ public void setAsyncgenFirstIter(Object asyncgenFirstIter) {
             this.asyncgenFirstIter = asyncgenFirstIter;
         }
 
+        public void resetNativeThreadLocalVarPointer() {
+            nativeThreadLocalVarRawPointer = 0;
+            nativeThreadLocalVarPointer = null;
+        }
+
         public void setNativeThreadLocalVarPointer(InteropLibrary interop, Object ptr) {
             // either unset or same
             assert nativeThreadLocalVarPointer == null || nativeThreadLocalVarPointer == ptr ||