@Override
 public void writeTo(StreamOutput out) throws IOException {
   super.writeTo(out);
   out.writeVInt(nodes.length);
   for (NodeHotThreads node : nodes) {
     node.writeTo(out);
   }
 }
 @Override
 public void readFrom(StreamInput in) throws IOException {
   super.readFrom(in);
   nodes = new NodeHotThreads[in.readVInt()];
   for (int i = 0; i < nodes.length; i++) {
     nodes[i] = NodeHotThreads.readNodeHotThreads(in);
   }
 }