小编典典

Tomcat8内存泄漏

tomcat

当我尝试在Java 8上停止tomcat8时,出现一些内存泄漏错误:

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;
    }
}

然后像这样启动和停止它:

@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);
    }
}

为什么我会收到所有这些内存泄漏错误?同样,当我运行关闭程序时,它不会关闭它,我必须手动终止该进程。

怎么了?


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2020-06-16

共1个答案

小编典典

不用担心。这是tomcat在检测到应用程序已启动Thread或自己创建的应用程序时输出的标准消息ThreadLocal。如果你终止关闭线程并删除
threadlocals 时不再需要它们,那么就没有问题。

为什么我会收到所有这些内存泄漏错误?同样,当我运行关闭程序时,它不会关闭它,我必须手动终止该进程。

我已经看到了这种现象,当应用程序启动时ScheduledExecutor(但是其他任何Thread/
都会发生这种情况TheadPool),并且没有关闭它contextDestroyed。因此,请检查您是否在应用程序/服务器停止时关闭线程。

现在,在您的具体问题上,
为什么服务器不会停止:JDBC驱动程序在JVM中注册为单例,并与所有Web应用程序共享。更多信息在这里。最好的解决方案是将MySQL驱动程序移动到Tomcat的/lib文件夹中。如果您无法做到这一点,则可以尝试一下,但这更像是骇客,而不是真正的解决方案。

2020-06-16