6814943: getcpool001 catches more than one JvmtiThreadState problem

Summary: Mark field volatile, use membars, and change access order to close race
Reviewed-by: dcubed, dholmes

src/share/vm/prims/jvmtiEventController.cpp

@@ -667,14 +667,13 @@ void
 JvmtiEventControllerPrivate::thread_ended(JavaThread *thread) {
   // Removes the JvmtiThreadState associated with the specified thread.
   // May be called after all environments have been disposed.
+  assert(JvmtiThreadState_lock->is_locked(), "sanity check");
 
   EC_TRACE(("JVMTI [%s] # thread ended", JvmtiTrace::safe_get_thread_name(thread)));
 
   JvmtiThreadState *state = thread->jvmti_thread_state();
-  if (state != NULL) {
-    MutexLocker mu(JvmtiThreadState_lock);
-    delete state;
-  }
+  assert(state != NULL, "else why are we here?");
+  delete state;
 }
 
 void JvmtiEventControllerPrivate::set_event_callbacks(JvmtiEnvBase *env,

src/share/vm/prims/jvmtiExport.cpp

@@ -2253,12 +2253,14 @@ void JvmtiExport::post_vm_object_alloc(JavaThread *thread,  oop object) {
 
 void JvmtiExport::cleanup_thread(JavaThread* thread) {
   assert(JavaThread::current() == thread, "thread is not current");
+  MutexLocker mu(JvmtiThreadState_lock);
 
-
-  // This has to happen after the thread state is removed, which is
-  // why it is not in post_thread_end_event like its complement
-  // Maybe both these functions should be rolled into the posts?
-  JvmtiEventController::thread_ended(thread);
+  if (thread->jvmti_thread_state() != NULL) {
+    // This has to happen after the thread state is removed, which is
+    // why it is not in post_thread_end_event like its complement
+    // Maybe both these functions should be rolled into the posts?
+    JvmtiEventController::thread_ended(thread);
+  }
 }
 
 void JvmtiExport::oops_do(OopClosure* f) {

src/share/vm/runtime/thread.cpp

@@ -31,6 +31,7 @@
 #include "compiler/compileBroker.hpp"
 #include "interpreter/interpreter.hpp"
 #include "interpreter/linkResolver.hpp"
+#include "jvmtifiles/jvmtiEnv.hpp"
 #include "memory/oopFactory.hpp"
 #include "memory/universe.inline.hpp"
 #include "oops/instanceKlass.hpp"
@@ -1699,7 +1700,7 @@ void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
     tlab().make_parsable(true);  // retire TLAB
   }
 
-  if (jvmti_thread_state() != NULL) {
+  if (JvmtiEnv::environments_might_exist()) {
     JvmtiExport::cleanup_thread(this);
   }
 

src/share/vm/runtime/thread.hpp

@@ -809,7 +809,7 @@ class JavaThread: public Thread {
   //
   // _vm_exited is a special value to cover the case of a JavaThread
   // executing native code after the VM itself is terminated.
-  TerminatedTypes       _terminated;
+  volatile TerminatedTypes _terminated;
   // suspend/resume support
   volatile bool         _suspend_equivalent;     // Suspend equivalent condition
   jint                  _in_deopt_handler;       // count of deoptimization