请问各位在生产环境如何让 tomcat 在处理完现有的任务之后正常退出？ 目前的状态是在执行 shutdown 脚本之后不会自动退出，显示有线程不能被正确停止，会导致内存泄露。

[qqwinds]

Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [/XXXXXX] registered the JDBC driver [com.alibaba.druid.proxy.DruidDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [/XXXXXX] 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.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] 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.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [pool-1-thread-1] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [pool-1-thread-2] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [pool-1-thread-3] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [pool-1-thread-4] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [Thread-7] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/XXXXXX] appears to have started a thread named [Thread-8] but has failed to stop it. This is very likely to create a memory leak.
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["http-bio-80"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["http-bio-8443"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["http-nio-443"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["ajp-bio-8009"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-bio-80"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-bio-8443"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-nio-443"]
Nov 02, 2017 3:11:39 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["ajp-bio-8009"]

现在已知产生这种情况的原因是有进程并未正常结束，阻止了 tomcat 的正常停止 请问各位在生产环境中一般是怎么配置的呢，如果有多台 tomcat 的话。

[Sypher]

以前遇到过，不是配置问题，是代码有问题啊，代码里面要关闭线程

[funky]

写个监听器实现 ServletContextListener 覆盖 contextDestroyed 方法

[iyangyuan]

检查代码才是正确选择，绝逼是有线程处于忙碌或阻塞状态，这基本上就能断定代码有 bug

[aqqwiyth]

System.exit(0)

[kaneg]

如果 shutdown 被某个线程给阻塞了， 比如加了 shutdown hook 之类的，那靠 tomcat 自己是没有可靠的办法退出了。这就需要外部强制其退出，比如用 kill -9 <pid>

[qqwinds]

@Sypher @iyangyuan 我也看出代码有问题了，问题大概在两个地方，第一个是 jdbc 没正确关闭，被强制注销。第二个应该是其他启用开始的线程的地方没有关闭。我不知道在这种情况下怎么进行调试，启用线程的地方有很多，而且基本都不是我写的。请问大佬们有什么好的找这些地方的方法不。

[qqwinds]

@aqqwiyth 这个不大合适吧。。。

[qqwinds]

@kaneg 我准备加 shutdown hook 了。。。之前一直用 kill -9 pid 的，后来发现，出现了好多问题，特别是在复杂业务的时候，业务执行完了，有时候没来得及返回结果就直接被 kill 了，客户端没收到信息，但是业务执行完了。。。比如这样

[qqwinds]

@funky 这个我没找到具体方案呢，百度未果。。。

[Sypher]

@qqwinds 除了 shutdown hook 之外，如果用框架的话，可以加一个 listener。在 contextDestroyed 里面加上你需要的代码。
类似
public class KafkaCunsumerListener implements ServletContextListener{
public void contextDestroyed(ServletContentEvent event){
//todo
}
}
最后把监听器陪在 web.xml 里面。

相当于把关闭线程绑定在 tomcat 上了

[qqwinds]

@Sypher 好的，我试一下，本来想设置守护线程，但是如果设置成守护线程还是不能合理的关闭

[qqwinds]

@iyangyuan 大佬，有个问题需要请教一下

for(;;){
code block

}
这种代码需要怎么正确关闭呢，里面是写了个获取微信 accessToken 的方法，然后采取的方案是获取完毕之后 wait 7200 秒，通过 jstack 发现这个线程在 tomcat shutdown 后仍然在 wait 中，并没有结束掉，多线程这块有点懵逼