Bug 50459

Summary: StandardContext.bindThread() and unbindThread() are not symmetrical and not limited to current thread
Product: Tomcat 6 Reporter: Sylvain Laurent <slaurent>
Component: CatalinaAssignee: Tomcat Developers Mailing List <dev>
Status: RESOLVED FIXED    
Severity: normal    
Priority: P2    
Version: 6.0.29   
Target Milestone: default   
Hardware: All   
OS: All   

Description Sylvain Laurent 2010-12-11 19:06:16 UTC 
As a side effect of my commit, I think I found a bug in StandardContext.bindThread() and unbindThread() methods in both tomcat 6 and 7 :

- the methods should be symmetrical : unbindThread should restore the Thread CCL after calling DirContextURLStreamHandler.unbind() and ContextBindings.unbindThread()
- StandardContext.bindThread() should call DirContextURLStreamHandler.bindThread() instead of DirContextURLStreamHandler.bind()
- StandardContext.unbindThread() should call DirContextURLStreamHandler.unbindThread() instead of DirContextURLStreamHandler.unbind()
Comment 1 Sylvain Laurent 2010-12-11 19:09:33 UTC 
oops, forgot the link to my initial commit that revealed the bug : http://svn.apache.org/viewvc?rev=1044145&view=rev
Comment 2 Sylvain Laurent 2010-12-11 19:12:12 UTC 
fix committed on trunk : http://svn.apache.org/viewvc?rev=1044746&view=rev
Comment 3 Mark Thomas 2010-12-12 16:22:28 UTC 
Moving to 6 now it is fixed in 7.
Comment 4 Sylvain Laurent 2010-12-12 17:56:31 UTC 
patch proposed for tomcat 6
Comment 5 Konstantin Kolinko 2010-12-12 18:43:04 UTC 
Looking at r1044746 and the patch proposed for TC6,
I think that that replacement of
 s/DirContextURLStreamHandler.bind(/DirContextURLStreamHandler.bindThread(/
 s/DirContextURLStreamHandler.unbind(/DirContextURLStreamHandler.unbindThread(/
is wrong.

See DirContextURLStreamHandler#get().

The difference is when a web application starts a child thread. That thread inherits TCCL from its parent and thus DirContextURLStreamHandler will recognize it when using CL-binding, but will not if thread-binding is used.
Comment 6 Sylvain Laurent 2010-12-13 17:42:40 UTC 
Actually the TCCL is properly bound in DirContextURLStreamHandler#clBindings when the application is started : DirContextURLStreamHandler.bind(ClassLoader, DirContext) is called from WebappLoader.startInternal() which itself is called during StandardContext.startInternal() (StandardContext.java rev 1044747 line 4863)

Before my fix, it was "pure luck" that the TCCL was still bound after StandardContext.startInternal() : it only worked because the TCCL was reverted _after_ calling DirContextURLStreamHandler.unbind() so that the latter tried to remove a classloader that had not been bound previously, thus leaving the webapp classloader properly bound.
Comment 7 Konstantin Kolinko 2010-12-19 19:48:15 UTC 
(In reply to comment #6)
OK, I understand it now. WebappLoader indeed manages that binding.
Comment 8 Mark Thomas 2011-01-05 09:18:11 UTC 
Fixed in 6.0.x and will be included in 6.0.30 onwards.