Author: markt
Date: Thu Mar 25 19:44:41 2010
New Revision: 927565
URL: http://svn.apache.org/viewvc?rev=927565&view=rev
Log:
Address various class-loader deadlock / sync issues
https://issues.apache.org/bugzilla/show_bug.cgi?id=44041
https://issues.apache.org/bugzilla/show_bug.cgi?id=48694
https://issues.apache.org/bugzilla/show_bug.cgi?id=48903
Whilst parallel class-loading would be a nice feature, the various issues that
have emerged have demonstrated that anything other than synchronized(this) is
likely to cause issues.
Parallel class-loading will be explored for Tomcat 7 (disabled by default) and
ported back to 6.0.x when proven to be stable.
Modified:
tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
tomcat/trunk/java/org/apache/jasper/servlet/JasperLoader.java
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=927565&r1=927564&r2=927565&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
(original)
+++ tomcat/trunk/java/org/apache/catalina/loader/WebappClassLoader.java Thu Mar
25 19:44:41 2010
@@ -1423,48 +1423,84 @@ public class WebappClassLoader
* @exception ClassNotFoundException if the class was not found
*/
@Override
- public Class<?> loadClass(String name, boolean resolve)
+ public synchronized Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException {
- synchronized (name.intern()) {
- if (log.isDebugEnabled())
- log.debug("loadClass(" + name + ", " + resolve + ")");
- Class<?> clazz = null;
-
- // Log access to stopped classloader
- if (!started) {
- try {
- throw new IllegalStateException();
- } catch (IllegalStateException e) {
- log.info(sm.getString("webappClassLoader.stopped", name),
e);
- }
+ if (log.isDebugEnabled())
+ log.debug("loadClass(" + name + ", " + resolve + ")");
+ Class<?> clazz = null;
+
+ // Log access to stopped classloader
+ if (!started) {
+ try {
+ throw new IllegalStateException();
+ } catch (IllegalStateException e) {
+ log.info(sm.getString("webappClassLoader.stopped", name), e);
}
-
- // (0) Check our previously loaded local class cache
- clazz = findLoadedClass0(name);
+ }
+
+ // (0) Check our previously loaded local class cache
+ clazz = findLoadedClass0(name);
+ if (clazz != null) {
+ if (log.isDebugEnabled())
+ log.debug(" Returning class from cache");
+ if (resolve)
+ resolveClass(clazz);
+ return (clazz);
+ }
+
+ // (0.1) Check our previously loaded class cache
+ clazz = findLoadedClass(name);
+ if (clazz != null) {
+ if (log.isDebugEnabled())
+ log.debug(" Returning class from cache");
+ if (resolve)
+ resolveClass(clazz);
+ return (clazz);
+ }
+
+ // (0.2) Try loading the class with the system class loader, to prevent
+ // the webapp from overriding J2SE classes
+ try {
+ clazz = system.loadClass(name);
if (clazz != null) {
- if (log.isDebugEnabled())
- log.debug(" Returning class from cache");
if (resolve)
resolveClass(clazz);
return (clazz);
}
-
- // (0.1) Check our previously loaded class cache
- clazz = findLoadedClass(name);
- if (clazz != null) {
- if (log.isDebugEnabled())
- log.debug(" Returning class from cache");
- if (resolve)
- resolveClass(clazz);
- return (clazz);
+ } catch (ClassNotFoundException e) {
+ // Ignore
+ }
+
+ // (0.5) Permission to access this class when using a SecurityManager
+ if (securityManager != null) {
+ int i = name.lastIndexOf('.');
+ if (i >= 0) {
+ try {
+ securityManager.checkPackageAccess(name.substring(0,i));
+ } catch (SecurityException se) {
+ String error = "Security Violation, attempt to use " +
+ "Restricted Class: " + name;
+ log.info(error, se);
+ throw new ClassNotFoundException(error, se);
+ }
}
-
- // (0.2) Try loading the class with the system class loader, to
prevent
- // the webapp from overriding J2SE classes
+ }
+
+ boolean delegateLoad = delegate || filter(name);
+
+ // (1) Delegate to our parent if requested
+ if (delegateLoad) {
+ if (log.isDebugEnabled())
+ log.debug(" Delegating to parent classloader1 " + parent);
+ ClassLoader loader = parent;
+ if (loader == null)
+ loader = system;
try {
- clazz = system.loadClass(name);
+ clazz = Class.forName(name, false, loader);
if (clazz != null) {
+ if (log.isDebugEnabled())
+ log.debug(" Loading class from parent");
if (resolve)
resolveClass(clazz);
return (clazz);
@@ -1472,53 +1508,36 @@ public class WebappClassLoader
} catch (ClassNotFoundException e) {
// Ignore
}
-
- // (0.5) Permission to access this class when using a
SecurityManager
- if (securityManager != null) {
- int i = name.lastIndexOf('.');
- if (i >= 0) {
- try {
-
securityManager.checkPackageAccess(name.substring(0,i));
- } catch (SecurityException se) {
- String error = "Security Violation, attempt to use " +
- "Restricted Class: " + name;
- log.info(error, se);
- throw new ClassNotFoundException(error, se);
- }
- }
- }
-
- boolean delegateLoad = delegate || filter(name);
-
- // (1) Delegate to our parent if requested
- if (delegateLoad) {
+ }
+
+ // (2) Search local repositories
+ if (log.isDebugEnabled())
+ log.debug(" Searching local repositories");
+ try {
+ clazz = findClass(name);
+ if (clazz != null) {
if (log.isDebugEnabled())
- log.debug(" Delegating to parent classloader1 " + parent);
- ClassLoader loader = parent;
- if (loader == null)
- loader = system;
- try {
- clazz = Class.forName(name, false, loader);
- if (clazz != null) {
- if (log.isDebugEnabled())
- log.debug(" Loading class from parent");
- if (resolve)
- resolveClass(clazz);
- return (clazz);
- }
- } catch (ClassNotFoundException e) {
- // Ignore
- }
+ log.debug(" Loading class from local repository");
+ if (resolve)
+ resolveClass(clazz);
+ return (clazz);
}
-
- // (2) Search local repositories
+ } catch (ClassNotFoundException e) {
+ // Ignore
+ }
+
+ // (3) Delegate to parent unconditionally
+ if (!delegateLoad) {
if (log.isDebugEnabled())
- log.debug(" Searching local repositories");
+ log.debug(" Delegating to parent classloader at end: " +
parent);
+ ClassLoader loader = parent;
+ if (loader == null)
+ loader = system;
try {
- clazz = findClass(name);
+ clazz = Class.forName(name, false, loader);
if (clazz != null) {
if (log.isDebugEnabled())
- log.debug(" Loading class from local repository");
+ log.debug(" Loading class from parent");
if (resolve)
resolveClass(clazz);
return (clazz);
@@ -1526,30 +1545,10 @@ public class WebappClassLoader
} catch (ClassNotFoundException e) {
// Ignore
}
-
- // (3) Delegate to parent unconditionally
- if (!delegateLoad) {
- if (log.isDebugEnabled())
- log.debug(" Delegating to parent classloader at end: " +
parent);
- ClassLoader loader = parent;
- if (loader == null)
- loader = system;
- try {
- clazz = Class.forName(name, false, loader);
- if (clazz != null) {
- if (log.isDebugEnabled())
- log.debug(" Loading class from parent");
- if (resolve)
- resolveClass(clazz);
- return (clazz);
- }
- } catch (ClassNotFoundException e) {
- // Ignore
- }
- }
-
- throw new ClassNotFoundException(name);
}
+
+ throw new ClassNotFoundException(name);
+
}
@@ -2537,7 +2536,7 @@ public class WebappClassLoader
if (clazz != null)
return clazz;
- synchronized (name.intern()) {
+ synchronized (this) {
clazz = entry.loadedClass;
if (clazz != null)
return clazz;
Modified: tomcat/trunk/java/org/apache/jasper/servlet/JasperLoader.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/jasper/servlet/JasperLoader.java?rev=927565&r1=927564&r2=927565&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/jasper/servlet/JasperLoader.java (original)
+++ tomcat/trunk/java/org/apache/jasper/servlet/JasperLoader.java Thu Mar 25
19:44:41 2010
@@ -89,7 +89,7 @@ public class JasperLoader extends URLCla
* @exception ClassNotFoundException if the class was not found
*/
@Override
- public Class<?> loadClass(final String name, boolean resolve)
+ public synchronized Class<?> loadClass(final String name, boolean resolve)
throws ClassNotFoundException {
Class<?> clazz = null;
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