NewRelic Agent 9.1.0在Tomcat 10.1中引发内存泄漏问题咨询

我们使用最新版New Relic Agent 9.1.0，在重新部署Web应用时发现内存泄漏问题。最初的警告日志如下：

07-Apr-2026 08:33:34.983 WARNING [http-1557107106] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [prod] appears to have started a
 thread named [New Relic Token Expiration Handler] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 java.base@17.0.18/jdk.internal.misc.Unsafe.park(Native Method)
 java.base@17.0.18/java.util.concurrent.locks.LockSupport.park(LockSupport.java:341)
 java.base@17.0.18/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionNode.block(AbstractQueuedSynchronizer.java:506)
 java.base@17.0.18/java.util.concurrent.ForkJoinPool.unmanagedBlock(ForkJoinPool.java:3465)
 java.base@17.0.18/java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3436)
 java.base@17.0.18/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1630)
 java.base@17.0.18/java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:435)
 java.base@17.0.18/java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1062)
 java.base@17.0.18/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1122)
 java.base@17.0.18/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
 java.base@17.0.18/java.lang.Thread.run(Thread.java:840)

随后持续出现非法访问日志：

08-Apr-2026 00:22:38.904 INFO [Thread-15843] org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. Could not load [org/apache/http/client/entity/DeflateInputStream.class]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
        java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [org/apache/http/client/entity/DeflateInputStream.class]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
                at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1396)
                at org.apache.catalina.loader.WebappClassLoaderBase.getResource(WebappClassLoaderBase.java:984)
                at com.newrelic.agent.util.asm.Utils.getClassResource(Utils.java:147)
                at com.newrelic.agent.util.asm.Utils.readClass(Utils.java:99)
                at com.newrelic.agent.instrumentation.context.InstrumentationContextClassMatcherHelper.isMatch(InstrumentationContextClassMatcherHelper.java:44)
                at com.newrelic.agent.instrumentation.context.ClassesMatcher$1.run(ClassesMatcher.java:55)
                at java.base/java.lang.Thread.run(Thread.java:840)

观察到New Relic保留了已停止的旧Web应用实例，尝试访问时触发插桩错误。以下是无需禁用New Relic的解决办法：

解决办法 #

1. 配置Agent的类加载隔离 #

修改newrelic.yml配置文件，启用类加载隔离设置，避免Agent线程持有Web应用类加载器的引用：

class_transformer:
  class_loader_isolation: true

该设置让Agent使用独立类加载器处理插桩逻辑，减少与Web应用类加载器的耦合，避免应用停止后Agent线程仍持有旧类加载器引用。

2. 手动触发Agent线程清理 #

在Web应用的停止钩子中调用New Relic的清理API，确保Agent线程被正确终止：

import com.newrelic.api.agent.NewRelic;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class NewRelicCleanupListener implements ServletContextListener {
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        NewRelic.shutdown();
    }
}

在web.xml中注册该监听器：

<listener>
    <listener-class>com.yourpackage.NewRelicCleanupListener</listener-class>
</listener>

此操作会触发Agent关闭流程，终止所有后台线程，释放对旧应用实例的引用。

3. 调整Tomcat线程清理策略 #

修改Tomcat的context.xml，启用强制线程清理：

<Context>
    <Loader clearReferencesThreads="true" clearReferencesStopThreads="true" />
</Context>

clearReferencesStopThreads参数会让Tomcat在应用停止时强制终止未正确停止的线程，包括New Relic后台线程，避免内存泄漏。

4. 跟进Agent版本更新 #

尽管当前使用9.1.0版本，仍可能存在未修复的线程泄漏bug，持续关注官方更新日志，一旦有对应修复版本发布，立即升级。

内容的提问来源于stack exchange，提问作者Simon