src/java.base/share/classes/java/io/ObjectStreamClass.java

*** 1183,1205 ****
              this.desc = desc;
              this.hasData = hasData;
          }
      }
  
      /**
       * Returns array of ClassDataSlot instances representing the data layout
       * (including superclass data) for serialized objects described by this
       * class descriptor.  ClassDataSlots are ordered by inheritance with those
       * containing "higher" superclasses appearing first.  The final
       * ClassDataSlot contains a reference to this descriptor.
       */
      ClassDataSlot[] getClassDataLayout() throws InvalidClassException {
          // REMIND: synchronize instead of relying on volatile?
!         if (dataLayout == null) {
!             dataLayout = getClassDataLayout0();
          }
!         return dataLayout;
      }
  
      private ClassDataSlot[] getClassDataLayout0()
          throws InvalidClassException
      {
--- 1183,1223 ----
              this.desc = desc;
              this.hasData = hasData;
          }
      }
  
+     private static final Unsafe U = Unsafe.getUnsafe();
+     private static final long   CDS_OFFSET;
+ 
+     static {
+         Field field = null;
+         try {
+             field = ObjectStreamClass.class.getDeclaredField("dataLayout");
+         } catch(NoSuchFieldException | SecurityException e) {
+         }
+         if(field == null) {
+             CDS_OFFSET = Unsafe.INVALID_FIELD_OFFSET;
+         } else {
+             CDS_OFFSET = U.objectFieldOffset(field);
+         }
+     }
+ 
      /**
       * Returns array of ClassDataSlot instances representing the data layout
       * (including superclass data) for serialized objects described by this
       * class descriptor.  ClassDataSlots are ordered by inheritance with those
       * containing "higher" superclasses appearing first.  The final
       * ClassDataSlot contains a reference to this descriptor.
       */
      ClassDataSlot[] getClassDataLayout() throws InvalidClassException {
          // REMIND: synchronize instead of relying on volatile?
!         ClassDataSlot[] slots = (ClassDataSlot[])U.getObjectAcquire(this, CDS_OFFSET);
!         if (slots == null) {
!             slots = getClassDataLayout0();
!             U.putObjectRelease(this, CDS_OFFSET, slots);
          }
!         return slots;
      }
  
      private ClassDataSlot[] getClassDataLayout0()
          throws InvalidClassException
      {