Author: markt
Date: Fri May 20 19:13:09 2016
New Revision: 1744786
URL: http://svn.apache.org/viewvc?rev=1744786&view=rev
Log:
Remove the ResourceBundle memory leak protection since I am as sure as I can be
that the original report was a false positive. The reasons I think this are:
- The GC roots related to ResourceBundle were all weak references.
- I can no longer produce the leak with the same (newer version) test
application and Java the original 1.8. If it was a GC bug it is fixed in any
version of Java that Tomcat 9 will use.
- We have a better understanding of JVM bugs that make some GC roots not
visible in profilers like YourKit.
Modified:
tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoaderBase.java
Modified:
tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoaderBase.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoaderBase.java?rev=1744786&r1=1744785&r2=1744786&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoaderBase.java
(original)
+++ tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoaderBase.java Fri
May 20 19:13:09 2016
@@ -23,7 +23,6 @@ import java.io.InputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.ref.Reference;
-import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URI;
@@ -52,8 +51,6 @@ import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
-import java.util.ResourceBundle;
-import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ThreadPoolExecutor;
@@ -77,7 +74,6 @@ import org.apache.tomcat.InstrumentableC
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.IntrospectionUtils;
import org.apache.tomcat.util.compat.JreCompat;
-import org.apache.tomcat.util.compat.JreVendor;
import org.apache.tomcat.util.res.StringManager;
/**
@@ -1526,13 +1522,6 @@ public abstract class WebappClassLoaderB
org.apache.juli.logging.LogFactory.release(this);
}
- // Clear the resource bundle cache
- // This shouldn't be necessary, the cache uses weak references but
- // it has caused leaks. Oddly, using the leak detection code in
- // standard host allows the class loader to be GC'd. This has been seen
- // on Sun but not IBM JREs. Maybe a bug in Sun's GC impl?
- clearReferencesResourceBundles();
-
// Clear the classloader reference in the VM's bean introspector
java.beans.Introspector.flushCaches();
@@ -2143,94 +2132,6 @@ public abstract class WebappClassLoaderB
}
}
-
- /**
- * 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 org.apache.jasper.servlet.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 out 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), getContextName()));
- }
- } catch (SecurityException e) {
- log.warn(sm.getString(
- "webappClassLoader.clearReferencesResourceBundlesFail",
- getContextName()), e);
- } catch (NoSuchFieldException e) {
- if (JreVendor.IS_ORACLE_JVM) {
- log.warn(sm.getString(
- "webappClassLoader.clearReferencesResourceBundlesFail",
- getContextName()), e);
- } else {
- log.debug(sm.getString(
- "webappClassLoader.clearReferencesResourceBundlesFail",
- getContextName()), e);
- }
- } catch (IllegalArgumentException e) {
- log.warn(sm.getString(
- "webappClassLoader.clearReferencesResourceBundlesFail",
- getContextName()), e);
- } catch (IllegalAccessException e) {
- log.warn(sm.getString(
- "webappClassLoader.clearReferencesResourceBundlesFail",
- getContextName()), e);
- }
- }
-
/**
* Find specified class in local repositories.
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