--- old/src/hotspot/share/gc/shared/concurrentGCThread.cpp	2019-03-25 10:50:16.704623214 +0100
+++ new/src/hotspot/share/gc/shared/concurrentGCThread.cpp	2019-03-25 10:50:16.487616222 +0100
@@ -23,72 +23,59 @@
  */
 
 #include "precompiled.hpp"
-#include "classfile/systemDictionary.hpp"
 #include "gc/shared/concurrentGCThread.hpp"
-#include "oops/instanceRefKlass.hpp"
-#include "oops/oop.inline.hpp"
 #include "runtime/init.hpp"
-#include "runtime/java.hpp"
-#include "runtime/javaCalls.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/orderAccess.hpp"
 #include "runtime/os.hpp"
 
 ConcurrentGCThread::ConcurrentGCThread() :
-  _should_terminate(false), _has_terminated(false) {
-};
+    _monitor(Monitor::leaf, "ConcurrentGCThread"),
+    _should_terminate(false),
+    _has_terminated(false) {}
 
 void ConcurrentGCThread::create_and_start(ThreadPriority prio) {
   if (os::create_thread(this, os::cgc_thread)) {
-    // XXX: need to set this to low priority
-    // unless "aggressive mode" set; priority
-    // should be just less than that of VMThread.
     os::set_priority(this, prio);
-    if (!_should_terminate) {
-      os::start_thread(this);
-    }
-  }
-}
-
-void ConcurrentGCThread::initialize_in_thread() {
-  this->set_active_handles(JNIHandleBlock::allocate_block());
-  // From this time Thread::current() should be working.
-  assert(this == Thread::current(), "just checking");
-}
-
-void ConcurrentGCThread::terminate() {
-  assert(_should_terminate, "Should only be called on terminate request.");
-  // Signal that it is terminated
-  {
-    MutexLockerEx mu(Terminator_lock,
-                     Mutex::_no_safepoint_check_flag);
-    _has_terminated = true;
-    Terminator_lock->notify();
+    os::start_thread(this);
   }
 }
 
 void ConcurrentGCThread::run() {
-  initialize_in_thread();
+  // Setup handle area
+  set_active_handles(JNIHandleBlock::allocate_block());
+
+  // Wait for initialization to complete
   wait_init_completed();
 
   run_service();
 
-  terminate();
+  // Signal thread has terminated
+  MonitorLockerEx ml(&_monitor);
+  OrderAccess::release_store(&_has_terminated, true);
+  ml.notify_all();
 }
 
 void ConcurrentGCThread::stop() {
-  // it is ok to take late safepoints here, if needed
-  {
-    MutexLockerEx mu(Terminator_lock);
-    assert(!_has_terminated,   "stop should only be called once");
-    assert(!_should_terminate, "stop should only be called once");
-    _should_terminate = true;
-  }
+  assert(!should_terminate(), "Invalid state");
+  assert(!has_terminated(), "Invalid state");
+
+  // Signal thread to terminate
+  OrderAccess::release_store(&_should_terminate, true);
 
   stop_service();
 
-  {
-    MutexLockerEx mu(Terminator_lock);
-    while (!_has_terminated) {
-      Terminator_lock->wait();
-    }
+  // Wait for thread to terminate
+  MonitorLockerEx ml(&_monitor);
+  while (!_has_terminated) {
+    ml.wait();
   }
 }
+
+bool ConcurrentGCThread::should_terminate() {
+  return OrderAccess::load_acquire(&_should_terminate);
+}
+
+bool ConcurrentGCThread::has_terminated() {
+  return OrderAccess::load_acquire(&_has_terminated);
+}