Many thanks for your answer. I found this issue discussing the leaks:
https://glassfish.dev.java.net/issues/show_bug.cgi?id=6082. If there are others could you please post the numbers?
Sorry if I'm insisting, but I'm slightly more concerned about these "non-classic leaks": It's true they won't cause the PermGen to grow without bounds, but they are still leaks, although less severe. I think it should be possible to be able to completely undeploy an application (i.e. all resources released including PermGen) without restarting the server (or without deploying some other applications hoping the current references will be overwritten).
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