Bernard,
It didn't get merged in yet but I am hoping that it soon will be. After the change is merged in, we will need to add the description of "managed PU" here.
By default, for each persistence unit definition, AS7 will create an EntityManagerFactory (with help from the Hibernate persistence provider). AS7 does that for providing container managed persistence contexts (implementing all of the EE container managed contracts) to the application. When you set the jboss.as.jpa.managed property to false, that tells AS7 to not create the EntityManagerFactory (so that Seam is the only creator of the EntityManagerFactory).
Each time that the EntityManagerFactory is created, EHCache is initialized (which fails the second time because the named cache is already in use).
Scott
Scott,
So if I didn't use Seam managed persistence context then I wouldn't have that issue?
Bernard,
Correct, the persistence.xml should be targetted for either Seam (2) managed persistence context or EE container managed persisence context but not both. This will help to avoid conflicts like you experienced (e.g. EHCache attempting to initialize the same cache twice.)
Scott
The AS7 nightly build should soon have the AS7-3423 fix (perhaps sometime tomorrow as the build machine is pretty busy tonight).
You will want to set the persistence unit property jboss.as.jpa.managed=false (doc link is here.)
<properties>
<property name="jboss.as.jpa.managed" value="false"/>
</properties>