[localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The

[localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [XXX] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it.

项目环境:tomcat8.5+ssm 在关闭web项目时发生一下警告:

 警告 [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [XXX] 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:144)
 com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:41)
28-Jan-2019 10:55:56.095 信息 [main] org.apache.coyote.AbstractProtocol.stop Stopping ProtocolHandler ["http-nio-8080"]
28-Jan-2019 10:55:56.096 信息 [main] org.apache.coyote.AbstractProtocol.stop Stopping ProtocolHandler ["ajp-nio-8009"]
28-Jan-2019 10:55:56.109 信息 [main] org.apache.coyote.AbstractProtocol.destroy Destroying ProtocolHandler ["http-nio-8080"]
28-Jan-2019 10:55:56.110 信息 [main] org.apache.coyote.AbstractProtocol.destroy Destroying ProtocolHandler ["ajp-nio-8009"]

根据StackOverFlow网站的内容找到了以下回答:

在我的web开发过程中，我只是在我的eclipse
IDE中关闭我的web应用程序，大约一分钟，我刚刚在我的eclipse控制台中看到了一个警告。

WARNING: The web application [/Spring.MVC] 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. Sep 06, 2014 8:31:55 PM
org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
WARNING: The web application [/Spring.MVC] 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(Unknown Source)
com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:40)
Sep 06, 2014 8:32:00 PM org.apache.catalina.core.ApplicationContext
log INFO: No Spring WebApplicationInitializer types detected on
classpath SLF4J: Failed to load class
“org.slf4j.impl.StaticLoggerBinder”. SLF4J: Defaulting to no-operation
(NOP) logger implementation SLF4J: See
http://www.slf4j.org/codes.html#StaticLoggerBinder for further
details. Sep 06, 2014 8:32:00 PM
org.apache.catalina.core.ApplicationContext log INFO: Initializing
Spring root WebApplicationContext Sep 06, 2014 8:32:03 PM
org.hibernate.jpa.internal.util.LogHelper
logPersistenceUnitInformation INFO: HHH000204: Processing
PersistenceUnitInfo [
name: personPU
…] 到目前为止它没有造成任何内存泄漏，我检查了我的VisualVM，一切正常，但是当我搜索更多关于这件事情时，我发现这个警告是由MySQL驱动程序没有释放资源或没有正确关闭引起的（我不知道该怎么说呢？我最后在SO
相关问题上发表了这篇文章

并且OP是正确
的，“不要担心它”的答案是不够的。这个警告困扰我，因为它可能会给我一些未来的持久性问题，这让我很担心，我尝试了OP编写的代码，但是我遇到了一个问题，我应该使用哪些库来使代码工作。这是我得到的东西…

import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Enumeration;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import org.hibernate.annotations.common.util.impl.LoggerFactory;
import com.mysql.jdbc.AbandonedConnectionCleanupThread;
@WebListener
public class ContextFinalizer implements ServletContextListener {

private static final Logger LOGGER = LoggerFactory.getLogger(ContextFinalizer.class);

public void contextInitialized(ServletContextEvent sce) {
}

public void contextDestroyed(ServletContextEvent sce) {
    Enumeration drivers = DriverManager.getDrivers();
    Driver d = null;
    while (drivers.hasMoreElements()) {
        try {
            d = drivers.nextElement();
            DriverManager.deregisterDriver(d);
            LOGGER.warn(String.format("Driver %s deregistered", d));
        }
        catch (SQLException ex) {
            LOGGER.warn(String.format("Error deregistering driver %s", d), ex);
        }
    }
    try {
        AbandonedConnectionCleanupThread.shutdown();
    }
    catch (InterruptedException e) {
        logger.warn("SEVERE problem cleaning up: " + e.getMessage());
        e.printStackTrace();
    }
  }
}

我只是想知道我需要哪些库，或者如果我正确使用正确的库来实现这一点，我甚至不知道我应该使用什么Logger，谢谢你的帮助，

得到23个赞的回答:

看到这个答案。似乎MySQL驱动程序应该{$TOMCAT]/lib在应用程序之间共享。检查每个应用程序是否包含它。至少它对我有用，我已经能够删除警告。

如果您使用Maven标记所提供的依赖项。


更新：
根本原因是Tomcat在垃圾收集驱动程序时遇到问题，因为它在多个应用程序的公共单件中注册。关闭一个应用程序不允许Tomcat释放驱动程序。看到这个答案。

解决:

将pom.xml中的mysql驱动依赖去掉（前提是要你的tomcat 中的lib目录中有这个jar包）