--- a/src/hotspot/share/classfile/javaClasses.cpp	Thu Apr 25 15:54:21 2019 -0700
+++ b/src/hotspot/share/classfile/javaClasses.cpp	Fri Apr 26 00:57:03 2019 -0400
@@ -1613,7 +1613,6 @@
 int java_lang_Thread::_tid_offset = 0;
 int java_lang_Thread::_thread_status_offset = 0;
 int java_lang_Thread::_park_blocker_offset = 0;
-int java_lang_Thread::_park_event_offset = 0 ;
 
 #define THREAD_FIELDS_DO(macro) \
   macro(_name_offset,          k, vmSymbols::name_name(), string_signature, false); \
@@ -1627,8 +1626,7 @@
   macro(_stackSize_offset,     k, "stackSize", long_signature, false); \
   macro(_tid_offset,           k, "tid", long_signature, false); \
   macro(_thread_status_offset, k, "threadStatus", int_signature, false); \
-  macro(_park_blocker_offset,  k, "parkBlocker", object_signature, false); \
-  macro(_park_event_offset,    k, "nativeParkEventPointer", long_signature, false)
+  macro(_park_blocker_offset,  k, "parkBlocker", object_signature, false)
 
 void java_lang_Thread::compute_offsets() {
   assert(_group_offset == 0, "offsets should be initialized only once");
@@ -1745,15 +1743,6 @@
   return java_thread->obj_field(_park_blocker_offset);
 }
 
-jlong java_lang_Thread::park_event(oop java_thread) {
-  return java_thread->long_field(_park_event_offset);
-}
-
-bool java_lang_Thread::set_park_event(oop java_thread, jlong ptr) {
-  java_thread->long_field_put(_park_event_offset, ptr);
-  return true;
-}
-
 const char* java_lang_Thread::thread_status_name(oop java_thread) {
   ThreadStatus status = (java_lang_Thread::ThreadStatus)java_thread->int_field(_thread_status_offset);
   switch (status) {

--- a/src/hotspot/share/classfile/javaClasses.hpp	Thu Apr 25 15:54:21 2019 -0700
+++ b/src/hotspot/share/classfile/javaClasses.hpp	Fri Apr 26 00:57:03 2019 -0400
@@ -371,7 +371,6 @@
   static int _tid_offset;
   static int _thread_status_offset;
   static int _park_blocker_offset;
-  static int _park_event_offset ;
 
   static void compute_offsets();
 
@@ -413,12 +412,6 @@
   // Blocker object responsible for thread parking
   static oop park_blocker(oop java_thread);
 
-  // Pointer to type-stable park handler, encoded as jlong.
-  // Should be set when apparently null
-  // For details, see unsafe.cpp Unsafe_Unpark
-  static jlong park_event(oop java_thread);
-  static bool set_park_event(oop java_thread, jlong ptr);
-
   // Java Thread Status for JVMTI and M&M use.
   // This thread status info is saved in threadStatus field of
   // java.lang.Thread java class.

--- a/src/hotspot/share/prims/unsafe.cpp	Thu Apr 25 15:54:21 2019 -0700
+++ b/src/hotspot/share/prims/unsafe.cpp	Fri Apr 26 00:57:03 2019 -0400
@@ -949,27 +949,16 @@
     (void) tlh.cv_internal_thread_to_JavaThread(jthread, &thr, &java_thread);
     if (java_thread != NULL) {
       // This is a valid oop.
-      jlong lp = java_lang_Thread::park_event(java_thread);
-      if (lp != 0) {
-        // This cast is OK even though the jlong might have been read
-        // non-atomically on 32bit systems, since there, one word will
-        // always be zero anyway and the value set is always the same
-        p = (Parker*)addr_from_java(lp);
-      } else {
-        // Not cached in the java.lang.Thread oop yet (could be an
-        // older version of library).
-        if (thr != NULL) {
-          // The JavaThread is alive.
-          p = thr->parker();
-          if (p != NULL) {
-            // Cache the Parker in the java.lang.Thread oop for next time.
-            java_lang_Thread::set_park_event(java_thread, addr_to_java(p));
-          }
-        }
+      if (thr != NULL) {
+        // The JavaThread is alive.
+        p = thr->parker();
       }
     }
   } // ThreadsListHandle is destroyed here.
 
+  // 'p' points to type-stable-memory if non-NULL. If the target
+  // thread terminates before we get here the new user of this
+  // Parker will get a 'spurious' unpark - which is perfectly valid.
   if (p != NULL) {
     HOTSPOT_THREAD_UNPARK((uintptr_t) p);
     p->unpark();

--- a/src/java.base/share/classes/java/lang/Thread.java	Thu Apr 25 15:54:21 2019 -0700
+++ b/src/java.base/share/classes/java/lang/Thread.java	Fri Apr 26 00:57:03 2019 -0400
@@ -194,11 +194,6 @@
     private final long stackSize;
 
     /*
-     * JVM-private state that persists after native thread termination.
-     */
-    private long nativeParkEventPointer;
-
-    /*
      * Thread ID
      */
     private final long tid;