怎么样解决Servlet与Ajax交互一直报status=parsererror的问题？

var jsonStr = {'clusterNum':2,'iterationNum':3,'runTimes':4};
  $.ajax({
   type: "post",
   //http://172.22.12.135:9000/Json.json
   url: "/LSHome/LSHome",
   dataType : 'json',
   data : jsonStr,
   success: function(data,textStatus){
    if(textStatus=="success"){ 
     alert("创建任务操作成功"+data);   
    }    
   },
   error: function(xhr,status,errMsg){
    alert("创建任务操作失败!");
   }
  });

<servlet>
  <servlet-name>LSHomeServlet</servlet-name>
  <servlet-class>com.ys.servlet.LSHomeServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>LSHomeServlet</servlet-name>
 <url-pattern>/LSHome</url-pattern>

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  //聚类数量
  String clusterNum = request.getParameter("clusterNum");
  //迭代次数
  String iterationNum = request.getParameter("iterationNum");
  //运行次数
  String runTimes = request.getParameter("runTimes");
  System.out.println("聚类数量为："+clusterNum+"---迭代次数:"+iterationNum+"---运行次数:"+runTimes);
  PrintWriter out = response.getWriter();   
  out.write("success");
  out.close(); 
 }

xhr = Object {readyState: 4, responseText: "success", status: 200, statusText: "OK"}

 PrintWriter out = response.getWriter();
String jsonStr = "{\"success\":\"OK\"}";
 out.write(jsonStr);