@Override
  public synchronized void sendResponseIfReady() throws IOException {
    // set param null to reduce memory pressure
    this.param = null;
    this.responder.doRespond(getConnection(), this);
  }
Call is done. Execution happened and we returned results to client. It is now safe to cleanup.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleServerCall.java