When a single message is received, we pass it to the thread pool for parsing, passing a copy of the byte array to the MyHandler runnable.
The parsing then creates a new Message and calls readFrom(). This method reads the headers and then creates a payload buffer of the size read from the input stream, then copies size bytes from the input stream to the mesage's payload.
This is an unneeded copy; as we already have a copy of the byte array, we only need to reference the byte array from the message and set the offset and length, saving us one copy of the buffer.