Servlet3.0新特性之异步处理

我想测试的是setTimeout后，当异步线程超时会有什么结果，第一次打开算正常但刷新之后就变成这样子。困扰了好久，求大神解答一下
代码如下：

 package test11;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import javax.servlet.AsyncContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns="/test1", asyncSupported=true)
public class test1 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public test1() {
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        //开始时间
        out.println(new Date() + "<br/>");
        AsyncContext asyncContext = request.startAsync();
        //设置超时时间0.5秒
        asyncContext.setTimeout(500);
        //开始异步处理
        asyncContext.start(new Run(asyncContext));
        //结束时间
        out.println(new Date()+ "<br/>");
        out.flush();
    }

}

class Run implements Runnable
{
    private AsyncContext asyncContext;
    public Run(AsyncContext asyncContext)
    {
        this.asyncContext = asyncContext;
    }

    @Override
    public void run() 
    {
        PrintWriter out = null;
        HttpServletRequest httpServletRequest = null;
        try {

            httpServletRequest = (HttpServletRequest) asyncContext.getRequest();
            HttpServletResponse httpServletResponse = (HttpServletResponse) asyncContext.getResponse();
            out = httpServletResponse.getWriter();
            //打印异步开始标志in
            out.println("in"+ "<br/>");
            //睡眠1秒，代表耗时的业务方法
            Thread.sleep(1000);
            //业务方法完成，打印完成标记out
            out.println("out"+ "<br/>");
            //输出完成时间
            out.println(new Date()+ "<br/>");
            asyncContext.dispatch("/index.jsp");
            } catch (Exception e) {
                e.printStackTrace();
            }
    }
}