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java – Tomcat8内存泄漏
当我尝试在 Java 8上停止tomcat8时,我收到一些内存泄漏错误:

org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] 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:40)
23-Jan-2015 08:18:10.202 WARNING [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [pool-5-thread-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread


23-Jan-2015 08:18:10.205 SEVERE [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.checkThreadLocalMapForLeaks The web application [ROOT] created a ThreadLocal with key of type [com.util.ThreadLocalProperties$1] (value [com.util.ThreadLocalProperties$1@2fafda6e]) and a value of type [java.util.Properties] (value [{}]) 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.

ThreadLocalProperties类是:

public class ThreadLocalProperties extends Properties {

    private static final long serialVersionUID = -4260632266508618756L;
    private final ThreadLocal<Properties> localProperties = new ThreadLocal<Properties>() {
        @Override
        protected Properties initialValue() {
            return new Properties();
        }
    };

    public ThreadLocalProperties(Properties properties) {
        super(properties);
    }

    @Override
    public String getProperty(String key) {
        String localValue = localProperties.get().getProperty(key);
        return localValue == null ? super.getProperty(key) : localValue;
    }

    @Override
    public Object setProperty(String key, String value) {
        return localProperties.get().setProperty(key, value);
    }

    public ThreadLocal<Properties> getThreadLocal() {
        return localProperties;
    }
}

我这样开始和停止它:

@WebListener()
public class GeneralListener implements ServletContextListener {

    ThreadLocalProperties threadLocalProperties = new ThreadLocalProperties(System.getProperties());

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        threadLocalProperties.getThreadLocal().remove();
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        System.setProperties(threadLocalProperties);
    }
}

为什么我会得到所有这些内存泄漏错误?同样,当我运行shutdown时,它不会关闭它,我必须手动终止进程.

怎么了?

最佳答案
没有什么可担心的.这是一个标准消息tomcat输出,当它检测到应用程序已启动它自己的Thread或创建一个ThreadLocal.如果在关闭时终止线程并在不再需要时删除threadlocals,那么就没有问题了.

Why would I get all this memory leaks errors? as well, when I run
shutdown, it doesn’t shut it down, I have to manually kill the
process.

我已经看到这种行为,当一个应用程序启动了ScheduledExecutor(但这将发生在任何其他Thread / TheadPool)并且没有在contextDestroyed上关闭它.因此,请检查您是否在应用程序/服务器停止时关闭了线程.

现在你的具体问题为什么服务器不会停止:
JDBC驱动程序在JVM中作为单例注册,并与所有Web应用程序共享.更多信息here.解决问题的最佳方法是在Tomcat的/ lib文件夹中移动MySQL驱动程序.如果你不能这样做,你可以尝试this,但它更像是一个黑客而不是一个真正的解决方案.

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