Exception in thread "HouseKeeper" java.lang.NullPointerException

最新推荐文章于 2022-11-04 20:50:55 发布

东东车

最新推荐文章于 2022-11-04 20:50:55 发布

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分类专栏：持久化相关文章标签： Java thread Servlet ITeye JVM

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文章详细介绍了使用Proxool时遇到的HouseKeeper线程NullPointerException问题，提供了一个简单有效的解决方法：在web.xml中配置LoadServlet，并在其中调用ProxoolFacade.shutdown()来显式关闭Proxool。通过多次点击页面触发bug的再现过程，最终通过此方法成功避免了bug的频繁出现。

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使用proxool了...版本0.9.1

时不时会报异常如下:

Exception in thread "HouseKeeper" java.lang.NullPointerException
	at org.logicalcobwebs.proxool.HouseKeeperController.getHouseKeeperToRun(HouseKeeperController.java:53)
	at org.logicalcobwebs.proxool.HouseKeeperThread.run(HouseKeeperThread.java:33)

参考:

[url]http://yang7527.iteye.com/blog/427512[/url]
[url]http://harbey.iteye.com/blog/888966[/url]
[url]http://topic.youkuaiyun.com/u/20080708/16/823ff6cc-a062-40e9-9858-169013138487.html[/url]

[quote]This is because Proxool is not being shutdown properly. If the JVM stops then Proxool recognises that and shuts down gracefully, but if you redeploy Proxool into some environments (for example, a servlet container) then Proxool needs to be explicitly told so by calling ProxoolFacade.shutdown(). If you have a servlet container then you could put it in the servlet's destroy() method. Alternatively, use the ServletConfigurator to both configure and shutdown Proxool[/quote]

[url]http://hi.baidu.com/dannyif/blog/item/66f4cdd749ca3f2806088b5a.html[/url]
今天应用启动后,页面点击几下就报出 Exception in thread "HouseKeeper" java.lang.NullPointerException; 多点几次会重复出现这bug, 然后在网上找到一个比较妙的解决办法:

LoadServlet.java :

package com.fsti.ec.common;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.logicalcobwebs.proxool.ProxoolFacade;

public class LoadServlet extends HttpServlet {
public void init() throws ServletException { 
     }

     public void destroy() { 
         //此处添加处理 
         ProxoolFacade.shutdown(); 
     }

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

     }

}

在web.xml 里的配置:

<!-- for resolving HouseKeeper bug-->
<servlet> 
    <servlet-name>loadServlet</servlet-name> 
    <servlet-class>com.fsti.ec.common.LoadServlet</servlet-class> 
    <load-on-startup>1</load-on-startup> 
</servlet>