src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/ObjectSynchronizer.java

@@ -53,10 +53,13 @@
      Mark mark = obj.getMark();
      if (mark.isUnlocked()) {
        // FIXME: can not generate marks in debugging system
        return mark.hash();
      } else if (mark.hasMonitor()) {
+       if (VM.getVM().getCommandLineFlag("LockingMode").getInt() == LockingMode.getLightweight()) {
+         return mark.hash();
+       }
        ObjectMonitor monitor = mark.monitor();
        Mark temp = monitor.header();
        return temp.hash();
      } else {
        if (Assert.ASSERTS_ENABLED) {