[TAP5-2592] Classloader issues under JBoss 6.X - 7.X (and I guess it affects most other application servers) - patch included

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 5.3.8, 5.4.1, 5.4.2, 5.4.3
• Component/s: plastic
• Labels: patch
• Flags: Patch
• Assignee: Unassigned
• Reporter: Luca Arzeni
• Created: 04/Dec/17 09:41
• Updated: 04/Dec/17 09:46

Description

few years ago, I raised an alert concerning the compatibility between Tapestry5 and JBoss; the thread was:

"Is tapestry plastic incompatible with JEE specs?"

https://mail-archives.apache.org/mod_mbox/tapestry-users/201512.mbox/%3Ctrinity-fc3b0e36-0402-4d71-b48a-4a464cbd6474-1449857158334@3capp-mailcom-lxa14%3E

At that time I found a workaround and concluded that there was no way to solve the issue, thinking that was a problem related to the jboss classloader (or, more generally, between an appserver classloader and the behaviour of plastic).

Few days ago, working on a new project under JBoss 7.0.0.GA, I was again badly hitted by this problem, but this time I investigated more thoroughly the issue and I found the source of all evil: the class "org.apache.tapestry5.internal.plastic.asm.ClassWriter" of plastic.

The classloader used to find (and load) the classes by plastic is really not compatible with an appserver. An appserver is required to enforce classloaded isolation and plastic ignores this.
Anyway plastic can be patched to solve the issue; here I attach a patch, please I ask to some developer to kindly forward and apply this patch to the 5.4.x branch and to the 5.5.

I also want to give thanks to these guys to help me to focus the problem:

https://stackoverflow.com/questions/42423907/unable-to-move-tapestry-jars-out-of-the-war-with-page-code-inside-the-war-still
https://blog.progs.be/50/tapestry-classloading-problems-on-jboss

Regards,
Luca Arzeni

• • • Here is the original code: ***

1752 protected String getCommonSuperClass(final String type1, final String type2) {
1753 Class<?> c, d;
1754 ClassLoader classLoader = getClass().getClassLoader();
1755 try

{ 1756 c = Class.forName(type1.replace('/', '.'), false, classLoader); 1757 d = Class.forName(type2.replace('/', '.'), false, classLoader); 1758 }

catch (Exception e)

{ 1759 throw new RuntimeException(e.toString()); 1760 }

1761 if (c.isAssignableFrom(d))

{ 1762 return type1; 1763 }

1764 if (d.isAssignableFrom(c))

{ 1765 return type2; 1766 }

1767 if (c.isInterface() || d.isInterface())

{ 1768 return "java/lang/Object"; 1769 }

else {
1770 do

{ 1771 c = c.getSuperclass(); 1772 }

while (!c.isAssignableFrom(d));
1773 return c.getName().replace('.', '/');
1774 }
1775 }

• • • Here is the patch: ***

1752 protected String getCommonSuperClass(final String type1, final String type2) {
1753 Class<?> c, d;
1754 ClassLoader classLoader = getClass().getClassLoader();
1755 try

{ 1756 c = Class.forName(type1.replace('/', '.'), false, classLoader); 1757 d = Class.forName(type2.replace('/', '.'), false, classLoader); 1758 }

catch (Exception e) {
// — ARZILLO PATCH BEGIN -----------------------------------------------------------

System.err.println("WARNING: type1:" + type1 + ", type2: " + type2 + ", exception: " + e + ", classLoader: " + classLoader +", attempting to use the classloader of the current thread");

classLoader = Thread.currentThread().getContextClassLoader();
if ( classLoader != null ) {

try

{ c = Class.forName(type1.replace('/', '.'), false, classLoader); d = Class.forName(type2.replace('/', '.'), false, classLoader); }

catch (Exception e_inner)

{ System.err.println("ERROR 1: type1:" + type1 + ", type2: " + type2 + ", e_inner: " + e_inner + ", classLoader: " + classLoader +", failed even using the classloader of the current thread"); throw new RuntimeException(e_inner.toString()); }

}
else

{ System.err.println("ERROR 2: type1:" + type1 + ", type2: " + type2 + ", exception: " + e + ", classLoader: " + classLoader +", unable to get the classloader of the current thread"); throw new RuntimeException(e.toString()); }

// — ARZILLO PATCH END -----------------------------------------------------------
1760 }
1761 if (c.isAssignableFrom(d))

{ 1762 return type1; 1763 }

1764 if (d.isAssignableFrom(c))

{ 1765 return type2; 1766 }

1767 if (c.isInterface() || d.isInterface())

{ 1768 return "java/lang/Object"; 1779 }

else {
1770 do

{ 1771 c = c.getSuperclass(); 1772 }

while (!c.isAssignableFrom(d));
1773 return c.getName().replace('.', '/');
1774 }
1775 }