#2, intercepting all, sounds like the best solution.
Is this something AspectJ could handle, via an aspect that uses around()
to intercept URLClassLoder construction (but somehow exclude our
creation of them) and constructs/returns our MultiParentClassloader instead?
To get started, you could use a before() aspect and log an error when
URLClassLoaders are created, just to prove that this could work....
http://www.eclipse.org/aspectj/doc/released/progguide/examples-basic.html
-Donald
Tim McConnell wrote:
Hi, There is at least one scenario using Axis2 and Geronimo that is
causing jarfiles to get locked on Windows such that a deployed WAR
cannot be either redeployed or uninstalled. Here is a brief description
of the failing scenario:
1. A WAR file containing various Axis2 jarfiles in the /lib directory
(axis2-kernel-1.4, axis2-adb-1.4, axis2-spring) is deployed on the
Tomcat version of Geronimo 2.1.3
2. Navigate to the deployed app's address to generate the WSDL for the
web service
3. Redeploy or uninstall of the WAR will now fail since all the jarfiles
in the WAR /lib directory are locked by Windows and cannot be deleted.
What appears to be happening is that there are three Axis2
URLClassLoaders in this scenario and at least two of them are creating
their own ClassPath and URLClassPath$JarLoader objects that apparently
are locking the jarfiles in the /lib directory. I know that Geronimo has
the JarFileClassloader and MultiParentClassloader classes to address
this problems of this type but unfortunately they don't really come into
play here since the Axis2 libraries are embedded in the WAR's /lib
directory. I also know that this has been a problem on Windows for a
long time (at least 2003 -- see Java Bug ID:4950148) and probably won't
be fixed in the JDK in the immediate future if ever. And finally I know
that this may not actually be a Geronimo problem but nevertheless
appears as just that to the Geronimo end-user(s).
Here is what I've tried up to now with varying degree of success:
1. Moved all the jarfiles out of WAR file into Geronimo's shared-lib
directory added a dependency to the geronimo-web.xml file. This
fortunately does work and provides a fairly simple work-around but still
doesn't fix the underlying problem.
2. Tried the corresponding Axis2-1.4.1 jarfiles (that were just recently
released) but they didn't fix the problem.
3. I was hoping that by using reflection I could clear out some of the
private variable in the ClassLoader to mitigate this problem. But this
causes errors in the JVM whenever the private variables (e.g. "classes)
are updated via reflection.
I wonder if there are other alternatives that I can pursue ?? Kevan has
suggested at least two:
1. Ask Axis2 to change their ClassLoader using the same techniques that
Geronimo employs with JarFileClassLoader and MultiParentClassLoader
2. Intercept instantiations of URLClassLoader in Geronimo and change
them to our own MultiParentClassLoader. I really like this idea since it
would be an all-encompassing solution and not specific to just Axis2,
but I don't know how difficult this might be.
Does anyone have any other suggestions and/or recommendations that I can
or should attempt ??
