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[Hibernate-issues] [Hibernate-JIRA] Commented: (HB-1064) CGLIB classes loaded even when reflection optimizer disabled
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From: <leg...@at...> - 2004-08-05 21:29:54
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The following comment has been added to this issue:
Author: Max Rydahl Andersen
Created: Thu, 5 Aug 2004 4:54 PM
Body:
okey - time to catch up on the hairy classloader issues (which is actually quite simple to solve ;)
The best resource I know of this is acutally a blog entry:
http://www.brainopolis.com/roller/comments/kduffey/Weblog/classloader_tips_part_1
Read especially the last sections reagarding thread context classloader and why you need that when dynamically creating/loading classes.
The problem is something that has popped up in many opensource projects - e.g. struts, velocity, digester, tomcat have had the same issues (and even worse the JDK it self ;)
One should ALWAYS use the current thread context class loader IFF it is set (non-null) and if that fails then use the default classloader of the default class loader!
Hibernate actually already have a method that does it mostly correct ;)
public static Class classForName(String name) throws ClassNotFoundException {
try {
return Thread.currentThread().getContextClassLoader().loadClass(name);
}
catch (Exception e) {
return Class.forName(name);
}
}
A better/safer implementation is:
public static Class classForName(String name) throws ClassNotFoundException {
if(Thread.currentThread().getContextClassLoader()!=null) {
try {
return Thread.currentThread().getContextClassLoader().loadClass(name);
}
catch (Exception e) {
return Class.forName(name);
}
} else {
Class.forName(name);
}
}
...I would suggest that cglib adds similar way of loading a class - otherwise if cglib, hibernate or e.g. component classes is located at different levels of the classloader hiearachy then we can get ClassNotFoundExceptions.
...hope that somewhat helps ;)
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View this comment:
http://opensource.atlassian.com/projects/hibernate/browse/HB-1064?page=comments#action_13947
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View the issue:
http://opensource.atlassian.com/projects/hibernate/browse/HB-1064
Here is an overview of the issue:
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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 4:54 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
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