java - Tomcat应用程序频繁崩溃可能是由于jdbc tomcat注册jdbc驱动程序

Question

每次启动和停止 tomcat 服务时，我都会在 tomcat-stderr.log 文件中收到以下信息:

SEVERE: The web application [/twinkle] registered the JDBC driver [net.sourceforge.jtds.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.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [Timer-0] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#3] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#4] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:00 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/twinkle] appears to have started a thread named [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#5] but has failed to stop it. This is very likely to create a memory leak.
Mar 01, 2016 2:02:01 AM org.apache.catalina.startup.HostConfig undeploy
INFO: Undeploying context [/twinkle]

我们的应用程序在生产环境中一直崩溃，我认为这即使不是主要原因，也可能是少数几个原因之一。

在我们的应用程序中，我注意到我们在许多地方创建了新的 Thread 对象；

FTPClient.java

217  Thread.sleep(5);
443  try { Thread.sleep(5); }
     catch( InterruptedException ie) {}
557  Thread.sleep(5);
576  Thread.sleep(1);

连接池.java

 private Thread m_CleanupThread = null; 
    protected ConnectionPool(String urlString, String user, String passwd) 
    {
       ...
       m_CleanupThread = new Thread(this); 
       m_CleanupThread.start();
    } 

还有更多像这样的 Thread 调用。

我应该使用thread.setContextClassLoader(null);

Answer 1

如果重新启动 Tomcat，那么这些内存泄漏警告将不会成为崩溃的原因。当您重新部署 Web 应用程序而不重新启动 Tomcat 时，内存泄漏警告是相关的，因为 Tomcat 将继续占用内存，而无法选择使用它或释放它(僵尸内存使用)，这反过来会为您的 Web 应用程序留下更少的内存(和 Tomcat)来使用。

至于“无法找到驱动程序类”错误:仔细看看this answer并确保 Web 应用程序本身不再包含“jdbc.jar”。另外，设置appropriate options对于 c3p0(将 privilegeSpawnedThreads 设置为 true 并将 contextClassLoaderSource 设置为 library)。

您可能还想尝试删除 Tomcat 的 work directory停止 Tomcat 之后和启动 Tomcat 之前。