src/share/vm/oops/instanceKlass.cpp

*** 1039,1049 ****
    instanceKlassHandle this_k(THREAD, this);
    return array_klass_impl(this_k, or_null, n, THREAD);
  }
  
  Klass* InstanceKlass::array_klass_impl(instanceKlassHandle this_k, bool or_null, int n, TRAPS) {
!   if (this_k->array_klasses() == NULL) {
      if (or_null) return NULL;
  
      ResourceMark rm;
      JavaThread *jt = (JavaThread *)THREAD;
      {
--- 1039,1050 ----
    instanceKlassHandle this_k(THREAD, this);
    return array_klass_impl(this_k, or_null, n, THREAD);
  }
  
  Klass* InstanceKlass::array_klass_impl(instanceKlassHandle this_k, bool or_null, int n, TRAPS) {
!   // Need load-acquire for lock-free read
!   if (this_k->array_klasses_acquire() == NULL) {
      if (or_null) return NULL;
  
      ResourceMark rm;
      JavaThread *jt = (JavaThread *)THREAD;
      {
*** 1052,1062 ****
        MutexLocker ma(MultiArray_lock, THREAD);
  
        // Check if update has already taken place
        if (this_k->array_klasses() == NULL) {
          Klass*    k = ObjArrayKlass::allocate_objArray_klass(this_k->class_loader_data(), 1, this_k, CHECK_NULL);
!         this_k->set_array_klasses(k);
        }
      }
    }
    // _this will always be set at this point
    ObjArrayKlass* oak = (ObjArrayKlass*)this_k->array_klasses();
--- 1053,1064 ----
        MutexLocker ma(MultiArray_lock, THREAD);
  
        // Check if update has already taken place
        if (this_k->array_klasses() == NULL) {
          Klass*    k = ObjArrayKlass::allocate_objArray_klass(this_k->class_loader_data(), 1, this_k, CHECK_NULL);
!         // use 'release' to pair with lock-free load
!         this_k->release_set_array_klasses(k);
        }
      }
    }
    // _this will always be set at this point
    ObjArrayKlass* oak = (ObjArrayKlass*)this_k->array_klasses();