[Hibernate-issues] [Hibernate-JIRA] Commented: (HB-1064) CGLIB classes loaded even when reflection optimizer disabled

[<leg...@at...>]

The following comment has been added to this issue:

     Author: Max Rydahl Andersen
    Created: Thu, 5 Aug 2004 5:04 PM
       Body:
Google is great ;)

http://sourceforge.net/forum/message.php?msg_id=1720229

The original thread were me and my colleague pointed out the exact same problem. I think only hibernate admins can read that posting from the forum so i'm also pasting it here:

"The "most correct" way to load a class in either J2EE or J2SE is to follow the pattern defined in the class below. This allows class loading to work properly in a context where there are more than one classloader (such as inside an app server).

---
public class ClassUtil {

static Class forName(String name) 
throws ClassNotFoundException
{
ClassLoader ctxLoader = null;
try {
ctxLoader = Thread.currentThread()
.getContextClassLoader();
return Class.forName(name, true, ctxLoader);

} catch(ClassNotFoundException ex) {
if(ctxLoader == null) { throw ex; }
} catch(SecurityException ex) {
}
return Class.forName(name);
}
}
---

For the second Class.forName to have any effect, the ClassUtil class should be loaded using the same class loader as the caller of this function. 

Therefore, this class should be included in the same linkage unit (class path element, .jar file or whatever) as the calling code. And thus; this class is (unfortunately) not really a good candidate to go into a generic class library.

At this point, most of the code in the JDK follows this pattern, but there are still many libraries out there that don't. This means that such libraries may not work correctly in a situation with more than one class loader."


---------------------------------------------------------------------
View this comment:
  http://opensource.atlassian.com/projects/hibernate/browse/HB-1064?page=comments#action_13948

---------------------------------------------------------------------
View the issue:
  http://opensource.atlassian.com/projects/hibernate/browse/HB-1064

Here is an overview of the issue:
---------------------------------------------------------------------
        Key: HB-1064
    Summary: CGLIB classes loaded even when reflection optimizer disabled
       Type: Bug

     Status: Reopened
   Priority: Minor

 Original Estimate: 5 minutes
 Time Spent: Unknown
  Remaining: 5 minutes

    Project: Hibernate2
 Components: 
             core
   Versions:
             2.1.3

   Assignee: Gavin King
   Reporter: Tim Motika

    Created: Mon, 5 Jul 2004 6:35 AM
    Updated: Thu, 5 Aug 2004 5:04 PM
Environment: All; ( win32 resin / issue when cglib dynamically loaded and not in system classpath, as on a webapp)

Description:
Running Hibernate from a webapp causes crash on ClassNotFoundException with the cglib
in the lib/ non-system path, even when the optimizer is turned
off, since it fails, being unable to load net.sf.cglib.reflect.FastClass for some container-related reason (CGLib is probably using Class.forName() which only loads system classes instead of getClass.getClassLoader().loadClass() ).

Container behavior aside, Hibernate is breaking encapsulation by loading cglib even when the feature is turned off, then not using it.

Suggested fix:

Only execute the calls to FastClass.create() conditionally
in these three files:

./net/sf/hibernate/persister/AbstractEntityPersister.java:756
./net/sf/hibernate/type/ComponentType.java:113
./net/sf/hibernate/util/ReflectHelper.java:156

Related: change usage of Class.forName() to getClass().getClassLoader().loadClass() in CGLIB so that the jar is
not pinned to being in the system classpath

Hrm.  Environmnet is *only* used in these files to check if the optimizer is on.  Seems like moving them over to configuration-based checking would be possible.

BTW, thanks for the great work on Hibernate!


Autopsy:
Stack trace, even when the optimizer has been disabled, and Environment.useReflectionOptimizer() returns false.

Error: net.sf.cglib.core.CodeGenerationException: java.lang.reflect.InvocationTargetException-->null
net.sf.cglib.core.CodeGenerationException: java.lang.reflect.InvocationTargetException-->null
	at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:208)
	at net.sf.cglib.reflect.FastClass$Generator.create(FastClass.java:92)
	at net.sf.cglib.reflect.FastClass.create(FastClass.java:74)
	at net.sf.hibernate.persister.AbstractEntityPersister.(AbstractEntityPersister.java:756)
	at net.sf.hibernate.persister.EntityPersister.(EntityPersister.java:714)
	at net.sf.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:42)
	at net.sf.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:137)
	at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:768)
	at org.tlala.site.HibernateUtil.start(HibernateUtil.java:183)
	at org.tlala.site.DBHome.startDB(DBHome.java:86)
	at org.tlala.site.DBHome.currentSession(DBHome.java:145)
	at org.tlala.site.DBHome.doBody(DBHome.java:292)
	at org.tlala.site.DBHome.service(DBHome.java:215)
	at org.tlala.site.DBHome.service(DBHome.java:176)
	at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
	at com.caucho.server.http.Invocation.service(Invocation.java:315)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:246)
	at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:164)
	at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
	at java.lang.Thread.run(Thread.java:534)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:324)
	at net.sf.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:411)
	at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:195)
	... 20 more
Caused by: java.lang.NoClassDefFoundError: net/sf/cglib/reflect/FastClass
	at java.lang.ClassLoader.defineClass0(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:537)
	... 26 more




---------------------------------------------------------------------
JIRA INFORMATION:
This message is automatically generated by JIRA.

If you think it was sent incorrectly contact one of the administrators:
   http://opensource.atlassian.com/projects/hibernate/secure/Administrators.jspa

If you want more information on JIRA, or have a bug to report see:
   http://www.atlassian.com/software/jira