org.apache.cxf.common.logging.JDKBugHacks Maven / Gradle / Ivy

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.cxf.common.logging;

import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLConnection;

import javax.imageio.ImageIO;
import javax.xml.parsers.DocumentBuilderFactory;

/**
 * This is called from LogUtils as LogUtils is almost always one of the VERY
 * first classes loaded in CXF so we can try and register to hacks/workarounds
 * for various bugs in the JDK.
 * 
 * Much of this is taken from work the Tomcat folks have done to find
 * places where memory leaks and jars are locked and such.
 * See:
 * http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/
 * core/JreMemoryLeakPreventionListener.java
 * 
 */
final class JDKBugHacks {
    private JDKBugHacks() {
        //not constructed
    }
    
    public static void doHacks() {
        ClassLoader orig = Thread.currentThread().getContextClassLoader();
        try {
            //set to the topmost non-null so things that grab the context classloader
            //won't get our classloader.
            ClassLoader ncl = orig;
            while (ncl.getParent() != null) {
                ncl = ncl.getParent();
            }
            Thread.currentThread().setContextClassLoader(ncl);
            
            try {
                //Trigger a call to sun.awt.AppContext.getAppContext()
                ImageIO.getCacheDirectory();
            } catch (Throwable t) {
                //ignore
            }
            try {
                // Several components end up opening JarURLConnections without first
                // disabling caching. This effectively locks the file.
                // JAXB does this and thus affects us pretty badly.
                // Doesn't matter that this JAR doesn't exist - just as long as
                // the URL is well-formed
                URL url = new URL("jar:file://dummy.jar!/");
                URLConnection uConn = url.openConnection();
                uConn.setDefaultUseCaches(false);
            } catch (Throwable e) {
                //ignore
            }
            try {
                //DocumentBuilderFactory seems to SOMETIMES pin the classloader
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                factory.newDocumentBuilder();
            } catch (Throwable e) {
                //ignore
            }
            // Several components end up calling:
            // sun.misc.GC.requestLatency(long)
            //
            // Those libraries / components known to trigger memory leaks due to
            // eventual calls to requestLatency(long) are:
            // - javax.management.remote.rmi.RMIConnectorServer.start()
            try {
                Class clazz = Class.forName("sun.misc.GC");
                Method method = clazz.getDeclaredMethod("requestLatency",
                        new Class[] {Long.TYPE});
                method.invoke(null, Long.valueOf(3600000));
            } catch (Throwable e) {
                //ignore
            }
        } finally {
            Thread.currentThread().setContextClassLoader(orig);
        }
        
    }

}