Our application is a Java-GWT application that uses Guice-Persist and Guice-Servlet extensively. We have never had a problem using the session-per-HTTPRequest feature of Guice-Persist which is similar to what Warp-persist originally used.
We are filtering our webapp through the PersistFilter class as per the documentation. Our persistence.xml file has transaction-type="RESOURCE_LOCAL" as per the Guice documentation here.
Now for some strange reason our PROD environment is showing the error
"Work already begun on this thread. Looks like you have called UnitOfWork.begin() twice without a balancing call to end() in between."
It looks like there is an issue where nested Units of work are not supported in Guice-Persist. LINK
We also recently moved from hibernate 3.6.3.Final to 4.1.4.Final. Not sure if his would have some sort of incompatibility with guice...
At this point we are totally in the dark as to why this would be happening.