Author: markt
Date: Thu Feb 11 18:09:08 2010
New Revision: 909097
URL: http://svn.apache.org/viewvc?rev=909097&view=rev
Log:
Improved memory leak prevention for resource ResourceBundle
Modified:
tomcat/trunk/java/org/apache/catalina/loader/LocalStrings.properties
tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
Modified: tomcat/trunk/java/org/apache/catalina/loader/LocalStrings.properties
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/loader/LocalStrings.properties?rev=909097&r1=909096&r2=909097&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/loader/LocalStrings.properties
(original)
+++ tomcat/trunk/java/org/apache/catalina/loader/LocalStrings.properties Thu
Feb 11 18:09:08 2010
@@ -35,6 +35,8 @@
webappClassLoader.stopped=Illegal access: this web application instance has
been stopped already. Could not load {0}. The eventual following stack trace
is caused by an error thrown for debugging purposes as well as to attempt to
terminate the thread which caused the illegal access, and has no functional
impact.
webappClassLoader.readError=Resource read error: Could not load {0}.
webappClassLoader.clearJbdc=A web application registered the JBDC driver [{0}]
but failed to unregister it when the web application was stopped. To prevent a
memory leak, the JDBC Driver has been forcibly unregistered.
+webappClassLoader.clearReferencesResourceBundlesCount=Removed [{0}]
ResourceBundle references from the cache
+webappClassLoader.clearReferencesResourceBundlesFail=Failed to clear
ResourceBundle references
webappClassLoader.clearRmiInfo=Failed to find class sun.rmi.transport.Target
to clear context class loader. This is expected on non-Sun JVMs.
webappClassLoader.clearRmiFail=Failed to clear context class loader referenced
from sun.rmi.transport.Target
webappClassLoader.clearThreadLocalDebug=A web application created a
ThreadLocal with key of type [{0}] (value [{1}]). The ThreadLocal has been
correctly set to null and the key will be removed by GC. However, to simplify
the process of tracing memory leaks, the key has been forcibly removed.
Modified: tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java?rev=909097&r1=909096&r2=909097&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
(original)
+++ tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java Thu Feb
11 18:09:08 2010
@@ -25,6 +25,7 @@
import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
@@ -47,6 +48,8 @@
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
+import java.util.ResourceBundle;
+import java.util.Set;
import java.util.Vector;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.jar.Attributes;
@@ -66,6 +69,7 @@
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleListener;
import org.apache.tomcat.util.res.StringManager;
+import org.apache.jasper.servlet.JasperLoader;
import org.apache.naming.JndiPermission;
import org.apache.naming.resources.Resource;
import org.apache.naming.resources.ResourceAttributes;
@@ -1773,6 +1777,9 @@
org.apache.juli.logging.LogFactory.release(this);
}
+ // Clear the resource bundle cache
+ clearReferencesResourceBundles();
+
// Clear the classloader reference in the VM's bean introspector
java.beans.Introspector.flushCaches();
@@ -2313,6 +2320,83 @@
/**
+ * Clear the {...@link ResourceBundle} cache of any bundles loaded by this
+ * class loader or any class loader where this loader is a parent class
+ * loader. Whilst {...@link ResourceBundle#clearCache()} could be used
there
+ * are complications around the {...@link JasperLoader} that mean a
reflection
+ * based approach is more likely to be complete.
+ *
+ * The ResourceBundle is using WeakReferences so it shouldn't be pinning
the
+ * class loader in memory. However, it is. Therefore clear ou the
+ * references.
+ */
+ private void clearReferencesResourceBundles() {
+ // Get a reference to the cache
+ try {
+ Field cacheListField =
+ ResourceBundle.class.getDeclaredField("cacheList");
+ cacheListField.setAccessible(true);
+
+ // Java 6 uses ConcurrentMap
+ // Java 5 uses SoftCache extends Abstract Map
+ // So use Map and it *should* work with both
+ Map<?,?> cacheList = (Map<?,?>) cacheListField.get(null);
+
+ // Get the keys (loader references are in the key)
+ Set<?> keys = cacheList.keySet();
+
+ Field loaderRefField = null;
+
+ // Iterate over the keys looking at the loader instances
+ Iterator<?> keysIter = keys.iterator();
+
+ int countRemoved = 0;
+
+ while (keysIter.hasNext()) {
+ Object key = keysIter.next();
+
+ if (loaderRefField == null) {
+ loaderRefField =
+ key.getClass().getDeclaredField("loaderRef");
+ loaderRefField.setAccessible(true);
+ }
+ WeakReference<?> loaderRef =
+ (WeakReference<?>) loaderRefField.get(key);
+
+ ClassLoader loader = (ClassLoader) loaderRef.get();
+
+ while (loader != null && loader != this) {
+ loader = loader.getParent();
+ }
+
+ if (loader != null) {
+ keysIter.remove();
+ countRemoved++;
+ }
+ }
+
+ if (countRemoved > 0 && log.isDebugEnabled()) {
+ log.debug(sm.getString(
+
"webappClassLoader.clearReferencesResourceBundlesCount",
+ Integer.valueOf(countRemoved)));
+ }
+ } catch (SecurityException e) {
+ log.error(sm.getString(
+ "webappClassLoader.clearReferencesResourceBundlesFail"),
e);
+ } catch (NoSuchFieldException e) {
+ log.error(sm.getString(
+ "webappClassLoader.clearReferencesResourceBundlesFail"),
e);
+ } catch (IllegalArgumentException e) {
+ log.error(sm.getString(
+ "webappClassLoader.clearReferencesResourceBundlesFail"),
e);
+ } catch (IllegalAccessException e) {
+ log.error(sm.getString(
+ "webappClassLoader.clearReferencesResourceBundlesFail"),
e);
+ }
+ }
+
+
+ /**
* Determine whether a class was loaded by this class loader or one of
* its child class loaders.
*/
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