org.mule.module.artifact.classloader

Class IBMMQResourceReleaser

java.lang.Object

org.mule.module.artifact.classloader.IBMMQResourceReleaser

All Implemented Interfaces:

ResourceReleaser

public class IBMMQResourceReleaser
extends Object
implements ResourceReleaser

A Utility class for releasing all the known references that may lead to a ClassLoader leak.

Constructor Summary

Constructors

Constructor and Description
IBMMQResourceReleaser(ClassLoader classLoader) Creates a new Instance of IBMMQResourceReleaser

Method Summary

Modifier and Type	Method and Description
void	cleanJULKnownLevels() The IBM MQ Driver registers custom Java Util Logging (JUL) Levels.
void	release() Attempts to release, during an Artifact undeployment, resources that were not explicitly released and could cause a memory leak.
void	removeMBeans() The IBM MQ Driver registers two MBeans for management.
void	removeThreadLocals() While analyzing the HeapDumps looking for the ClassLoader Leak causes, there were ThreadLocal references to driver classes in threads that do not belong to the application being disposed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IBMMQResourceReleaser

public IBMMQResourceReleaser(ClassLoader classLoader)

Creates a new Instance of IBMMQResourceReleaser

Parameters:

classLoader - ClassLoader which loaded the IBM MQ Driver.

Method Detail

release

public void release()

Description copied from interface: ResourceReleaser

Attempts to release, during an Artifact undeployment, resources that were not explicitly released and could cause a memory leak.

Specified by:

release in interface ResourceReleaser

removeMBeans

public void removeMBeans()

The IBM MQ Driver registers two MBeans for management. When disposing the application / domain, this beans keep references to classes loaded by this ClassLoader. When the application is removed, the ClassLoader is leaked due this references. The two known mbeans are * TraceControl * PropertyStoreControl

cleanJULKnownLevels

public void cleanJULKnownLevels()

The IBM MQ Driver registers custom Java Util Logging (JUL) Levels. the JUL Classes are loaded by system Classloader. So there are references left from outside the application context. So, it retains instances and leaks the application ClassLoader. This method removes the knownLevels registered by the Classes Loaded by the driver ClassLoader. This only applies to JDK8. * https://bugs.openjdk.java.net/browse/JDK-6543126 * https://github.com/AdoptOpenJDK/openjdk-jdk8u/blob/master/jdk/src/share/classes/java/util/logging/Level.java#L534 * https://github.com/AdoptOpenJDK/openjdk-jdk11/blob/master/src/java.logging/share/classes/java/util/logging/Level.java#L563

removeThreadLocals

public void removeThreadLocals()

While analyzing the HeapDumps looking for the ClassLoader Leak causes, there were ThreadLocal references to driver classes in threads that do not belong to the application being disposed. This references leads to a ClassLoader leak. This method removes the thread local references to instances of classes loaded by the driver classloader.