启动tomcat8提示内存泄漏问题解决

故障起源

今天启动tomcat8，发现网址访问不了，网页提示：

HTTP Status 404 - /zsale-web/

message /zsale-web/

description The requested resource is not available.

tomcat8

于是打开catalina.out查看日志。

26-Oct-2015 11:23:26.735 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [zsale-web-0.0.1-SNAPSHOT] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:

java.lang.Object.wait(Native Method)

java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:142)

com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:43)

26-Oct-2015 11:23:26.737 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [zsale-web-0.0.1-SNAPSHOT] appears to have started a thread named [Druid-ConnectionPool-Create-2108774764] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:

sun.misc.Unsafe.park(Native Method)

java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)

java.util.concurrent.locks.AbstractQueuedSynchronizerConditionObject.await(AbstractQueuedSynchronizer.java:2039)com.alibaba.druid.pool.DruidDataSourceCreateConnectionThread.run(DruidDataSource.java:1868)

tomcat7

于是换成了tomcat7再尝试一番。还是报错，报错信息大同小异。

2015-10-26 14:21:07 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc

严重: The web application [/zsale-web] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

意思是：注册了com.mysql.jdbc.Driver以后当应用停止时无法注销，为了防止内存泄漏，jdbc驱动被强制注销。

这种错误，是由于从tomcat6.0.24版本开始，在server.xml中增加了对内存泄漏的检测。

解决方法有两种：

把server.xml的把这个监听去掉

另一个方法是换成6.0.24版本以下的tomcat（比如6.0.20）

但是我尝试把server.xml的listener去掉不行，报错依旧。

网上参考网址：

http://liu-yuan-qing.blog.163.com/blog/static/652827872012613102323662/

http://bbs.csdn.net/topics/390336957?page=1

http://blog.csdn.net/a19881029/article/details/36419229

tomcat6.0.20

tomcat6.0.20

…javax.servlet-api-3.0.1.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class

tomcat6终于不报这个错误了，但是由于servlet版本的问题报了另一个错误。

最后终于搞定，发现并不是这个错误导致网址访问不了，而是另外一个错误(连接不上数据库主机)，这个错误并不是看catalina.out，而是要看localhost.2015-10-27.log：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘dataSource’ defined in file [/ngbss/webapp/tomcat6/tomcat-zsale/webapps/zsale-web/WEB-INF/classes/spring/spring-context-datasource.xml]: Invocation of init method failed; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Caused by: java.net.ConnectException: Connection timed out

总结

当发现tomcat提示内存泄漏错误，有三种解决方法：

如果能解决掉内存泄漏最好，即使是误报也尽量修改掉

把tomcat的listener注释掉

换6.0.20以下的版本

另外需要注意的是，这种报错并不影响应用的启动，如果启动不了，那需要查找别的原因。

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本文出自:【ouyida3的博客】

2015.10.28