Threads are going to be renewed over time to try and avoid a probable mem，内存溢出错误

[zhangweitaylor]

测试运行的时候，程序运行正常，正式上线后，服务器运行一段时候后，报下面的内容溢出错误。必须重启APACHE才可以解决；而且这个问题越来越突出了，麻烦高手帮忙解决下。谢谢。
org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
严重: The web application [] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@4a6a0f1b]) and a value of type [com.microsoft.sqlserver.jdbc.SQLServerConnection] (value [ConnectionID:32]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
1）服务器内存资源监控了下。内存占用率并不高。
2）查了下网上资料，有的讲是数据库链接没有释放，但程序中数据库链接很多，很难逐一排查；
请问：
1）原因可能是什么？如何解决？
2）如果确实是链接没有释放，请问如何找到是哪个地方的数据库链接没有释放。

[zhangweitaylor]

帮忙顶下贴，顶者有分，谢谢。

[zhangweitaylor]

补充下完整的错误日志： 严重: The web application [] registered the JDBC driver [com.microsoft.sqlserver.jdbc.SQLServerDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered. 四月 11, 2017 10:46:44 上午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads 严重: The web application [] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation. 四月 11, 2017 10:46:44 上午 org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks 严重: The web application [] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@240221b3]) and a value of type [com.legeritsoft.framework.pub.util.UserState] (value [