Regional classloaders and state transfer

[fredrikj]

We are currently using the 2.0 beta 2 release, and have some problem with the state transfer.

We are using regional based classloaders with an example cache like:

/a/ -> ClassLoader A
/b/ -> ClassLoader B

The startup sequence of the cache looks like:

1. Create cache
2. Register classloaders
3. Start the cache

Now, we startup Cache #1 and everything is working well. We add some ClassLoader A specific objects under /a/... and can read and write them correctly. Placing ClassLoader B specific objects under /b/... also works fine.

Then we start Cache #2 using the same start sequence as above, but then we run into problems. Cache #1 has objects in it's cache so a state transfer is initialized. The regions have been initialized in Cache #2 with proper classloaders so that should be fine. However, the state transfer from Cache #1 is triggered on the root '/'.

When Cache #2 gets the initial state transfer it goes a little like this:

1. Do I have regional based classloaders? yes.
2. Do I have a classloader defined for region '/'? no.
3. Use default classloader.
4. ClassNotFoundException

The class not found is of course due to the fact that objects under /a/... will require ClassLoader A. The steps are of course my interpretation from stepping the code in a debugger, I might be wrong.

Any feedback regarding this would be much appreciated, I am not really sure yet on how to solve the problem if the state transfer is for the whole cache with the root node as reference.

[manik]

Hi - do you have a unit test for this?

Does your test correspond to any of the existing test cases in http://fisheye.jboss.com/browse/JBoss/JBossCache/tests/functional/org/jboss/cache/marshall?

[brian.stansberry]

The way to handle this use case is configure the cache with "InactiveOnStartup" set to true. Then:

1) Create cache
2) Start cache. (no state transfer occurs due to "InactiveOnStartup")
3) For each region:
a) register classloader
b) activateRegion (state transfer for that region occurs and uses the correct classloader)

It would be nice to support doing it the way you described. Requires better integration between the StateTransferManager and the RegionManager.