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Monitoring of JavaEE applications
/*
* Copyright 2008-2017 by Emeric Vernat
*
* This file is part of Java Melody.
*
* Licensed 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 net.bull.javamelody.internal.model;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import javax.management.ObjectName;
import net.bull.javamelody.internal.common.I18N;
/**
* Classe d'attachement dynamique utilisée ici pour obtenir l'histogramme de la mémoire.
*
Cette classe nécessite tools.jar du jdk pour être exécutée (ok dans tomcat),
* mais pas pour être compilée.
*
@see VirtualMachine
* @author Emeric Vernat
*/
public final class VirtualMachine {
private static boolean enabled = isSupported();
// singleton initialisé à la demande
private static Object jvmVirtualMachine;
private VirtualMachine() {
super();
}
/**
* @return true si heapHisto supporté.
*/
public static boolean isSupported() {
// pour nodes Jenkins, on réévalue sans utiliser de constante
final String javaVendor = System.getProperty("java.vendor");
return javaVendor.contains("Sun") || javaVendor.contains("Oracle")
|| javaVendor.contains("Apple") || isJRockit();
}
/**
* @return true si JVM JRockit
*/
public static boolean isJRockit() {
// pour nodes Jenkins, on réévalue sans utiliser de constante
return System.getProperty("java.vendor").contains("BEA");
}
/**
* @return false si non supporté ou si un attachement ou un histogramme a échoué,
* true si supporté et pas essayé ou si réussi
*/
public static synchronized boolean isEnabled() { // NOPMD
return enabled;
}
/**
* @return Singleton initialisé à la demande de l'instance de com.sun.tools.attach.VirtualMachine,
* null si enabled est false
* @throws Exception e
*/
public static synchronized Object getJvmVirtualMachine() throws Exception { // NOPMD
// si hotspot retourne une instance de sun.tools.attach.HotSpotVirtualMachine
// cf http://www.java2s.com/Open-Source/Java-Document/6.0-JDK-Modules-sun/tools/sun/tools/attach/HotSpotVirtualMachine.java.htm
// et sous windows : sun.tools.attach.WindowsVirtualMachine
if (jvmVirtualMachine == null) {
// on utilise la réflexion pour éviter de dépendre de tools.jar du jdk à la compilation
final Class virtualMachineClass = findVirtualMachineClass();
final Method attachMethod = virtualMachineClass.getMethod("attach", String.class);
final String pid = PID.getPID();
try {
jvmVirtualMachine = invoke(attachMethod, null, pid);
} finally {
enabled = jvmVirtualMachine != null;
}
}
return jvmVirtualMachine;
}
private static Class findVirtualMachineClass() throws Exception { // NOPMD
// méthode inspirée de javax.tools.ToolProvider.Lazy.findClass
// http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b27/javax/tools/ToolProvider.java#ToolProvider.Lazy.findClass%28%29
final String virtualMachineClassName = "com.sun.tools.attach.VirtualMachine";
try {
// try loading class directly, in case tools.jar is in the classpath
return Class.forName(virtualMachineClassName);
} catch (final ClassNotFoundException e) {
// exception ignored, try looking in the default tools location (lib/tools.jar)
File file = new File(System.getProperty("java.home"));
if ("jre".equalsIgnoreCase(file.getName())) {
file = file.getParentFile();
}
final String[] defaultToolsLocation = { "lib", "tools.jar" };
for (final String name : defaultToolsLocation) {
file = new File(file, name);
}
// if tools.jar not found, no point in trying a URLClassLoader
// so rethrow the original exception.
if (!file.exists()) {
throw e;
}
final URL url = file.toURI().toURL();
final ClassLoader cl;
// if (ClassLoader.getSystemClassLoader() instanceof URLClassLoader) {
// // The attachment API relies on JNI, so if we have other code in the JVM that tries to use the attach API
// // (like the monitoring of another webapp), it'll cause a failure (issue 398):
// // "UnsatisfiedLinkError: Native Library C:\Program Files\Java\jdk1.6.0_35\jre\bin\attach.dll already loaded in another classloader
// // [...] com.sun.tools.attach.AttachNotSupportedException: no providers installed"
// // So we try to load tools.jar into the system classloader, so that later attempts to load tools.jar will see it.
// cl = ClassLoader.getSystemClassLoader();
// // The URLClassLoader.addURL method is protected
// final Method addURL = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
// addURL.setAccessible(true);
// addURL.invoke(cl, url);
// } else {
final URL[] urls = { url };
cl = URLClassLoader.newInstance(urls);
// }
return Class.forName(virtualMachineClassName, true, cl);
}
}
/**
* Détachement du singleton.
* @throws Exception e
*/
public static synchronized void detach() throws Exception { // NOPMD
if (jvmVirtualMachine != null) {
final Class virtualMachineClass = jvmVirtualMachine.getClass();
final Method detachMethod = virtualMachineClass.getMethod("detach");
jvmVirtualMachine = invoke(detachMethod, jvmVirtualMachine);
jvmVirtualMachine = null;
}
}
/**
* @return flux contenant l'histogramme mémoire comme retourné par jmap -histo
* @throws Exception e
*/
public static InputStream heapHisto() throws Exception { // NOPMD
if (!isSupported()) {
throw new IllegalStateException(I18N.getString("heap_histo_non_supporte"));
}
if (!isEnabled()) {
throw new IllegalStateException(I18N.getString("heap_histo_non_actif"));
}
try {
final ObjectName objectName = new ObjectName(
"com.sun.management:type=DiagnosticCommand");
final String gcClassHistogram = (String) MBeansAccessor.invoke(objectName,
"gcClassHistogram", new Object[] { null }, new Class[] { String[].class });
return new ByteArrayInputStream(gcClassHistogram.getBytes("UTF-8"));
} catch (final Exception e1) {
// MBean "DiagnosticCommand" not found (with JDK 7 for example),
// continue with VM attach method
try {
final Class virtualMachineClass = getJvmVirtualMachine().getClass();
final Method heapHistoMethod = virtualMachineClass.getMethod("heapHisto",
Object[].class);
return (InputStream) invoke(heapHistoMethod, getJvmVirtualMachine(),
new Object[] { new Object[] { "-all" } });
} catch (final ClassNotFoundException e) {
// si on obtient ClassNotFoundException alors que heap histo est "supporté"
// alors c'est que la jvm est un JRE et non un JDK (certainement avec tomcat) :
// on le signale à l'administrateur car il peut simplement installer un JDK et changer JAVA_HOME,
throw new IllegalStateException(I18N.getString("heap_histo_jre"), e);
} catch (final Exception e) {
if ("Can not attach to current VM".equals(e.getMessage())) {
throw new IllegalStateException(I18N.getString("allowAttachSelf"), e);
}
// si on obtient com.sun.tools.attach.AttachNotSupportedException: no providers installed
// alors c'est idem (javaws dans Jenkins nodes par exemple)
if ("com.sun.tools.attach.AttachNotSupportedException"
.equals(e.getClass().getName())) {
throw new IllegalStateException(I18N.getString("heap_histo_jre"), e);
}
throw e;
}
}
}
/**
* @return l'histogramme mémoire
* @throws Exception e
*/
public static HeapHistogram createHeapHistogram() throws Exception { // NOPMD
final InputStream input = heapHisto();
try {
return new HeapHistogram(input, isJRockit());
} finally {
input.close();
}
}
private static Object invoke(Method method, Object object, Object... args) throws Exception { // NOPMD
try {
return method.invoke(object, args);
} catch (final InvocationTargetException e) {
if (e.getCause() instanceof Exception) {
throw (Exception) e.getCause();
} else if (e.getCause() instanceof Error) {
throw (Error) e.getCause();
} else {
throw new Exception(e.getCause()); // NOPMD
}
}
}
// Note : on pourrait aussi charger dynamiquement un agent avec jvmVirtualMachine.loadAgent
// (en générant un jar temporaire avec ZipFile à partir de
// getClass().getResourceAsStream(getClass().getName() + ".class"), d'un manifest contenant Agent-Class)
// pour obtenir la taille sans ses références d'un objet (Instrumentation.getObjectSize)
// ou pour ajouter de la programmation par aspect à la volée (datasource jdbc, façades...)
// (addClassTransformer(new org.aspectj.weaver.loadtime.ClassPreProcessorAgentAdapter())
// ou loadAgent("aspectjweaver.jar") par exemple).
// Voir http://java.sun.com/javase/6/docs/api/java/lang/instrument/package-summary.html?is-external=true
// private static final String MONITORING_INSTRUMENTATION_KEY = "javamelody.instrumentation";
// private static Instrumentation instrumentation;
//
// public void loadAgent(String jarFile) throws AgentLoadException, AgentInitializationException,
// IOException {
// try {
// jvmVirtualMachine.loadAgent(jarFile);
// } finally {
// instrumentation = (Instrumentation) System.getProperties().get(
// MONITORING_INSTRUMENTATION_KEY);
// System.getProperties().remove(MONITORING_INSTRUMENTATION_KEY);
// }
// }
//
// public static void agentmain(@SuppressWarnings("unused") String agentArgs, Instrumentation inst) {
// System.getProperties().put(MONITORING_INSTRUMENTATION_KEY, inst);
// }
//
// public long getObjectSize(Object objectToSize) {
// return instrumentation.getObjectSize(objectToSize);
// }
//
// public void addClassTransformer(ClassFileTransformer transformer, boolean canRetransform) {
// instrumentation.addTransformer(transformer, canRetransform);
// }
}