--- a/src/hotspot/os/windows/os_windows.cpp	Tue Feb 05 13:21:59 2019 -0500
+++ b/src/hotspot/os/windows/os_windows.cpp	Tue Feb 05 15:12:13 2019 -0500
@@ -5277,6 +5277,55 @@
   SetEvent(_ParkEvent);
 }
 
+// Platform Monitor implementation
+
+os::PlatformMonitor::PlatformMonitor() {
+  InitializeConditionVariable(&_cond);
+  InitializeCriticalSection(&_mutex);
+}
+
+os::PlatformMonitor::~PlatformMonitor() {
+  DeleteCriticalSection(&_mutex);
+}
+
+void os::PlatformMonitor::lock() {
+  EnterCriticalSection(&_mutex);
+}
+
+void os::PlatformMonitor::unlock() {
+  LeaveCriticalSection(&_mutex);
+}
+
+bool os::PlatformMonitor::try_lock() {
+  return TryEnterCriticalSection(&_mutex);
+}
+
+// Must already be locked
+int os::PlatformMonitor::wait(jlong millis) {
+  assert(millis >= 0, "negative timeout");
+  int ret = OS_TIMEOUT;
+  int status = SleepConditionVariableCS(&_cond, &_mutex,
+                                        millis == 0 ? INFINITE : millis);
+  if (status != 0) {
+    ret = OS_OK;
+  }
+  #ifndef PRODUCT
+  else {
+    DWORD err = GetLastError();
+    assert(err == ERROR_TIMEOUT, "SleepConditionVariableCS: %ld:", err);
+  }
+  #endif
+  return ret;
+}
+
+void os::PlatformMonitor::notify() {
+  WakeConditionVariable(&_cond);
+}
+
+void os::PlatformMonitor::notify_all() {
+  WakeAllConditionVariable(&_cond);
+}
+
 // Run the specified command in a separate process. Return its exit value,
 // or -1 on failure (e.g. can't create a new process).
 int os::fork_and_exec(char* cmd, bool use_vfork_if_available) {