T4: when a session http is closed?, where a session http is closed?

[César Augusto Mateus]

is some way to capture the moment at which a session HTTP is closed?
(perhaps with a service in hivemind)
I need to do this: clear a threadLocal just when the session http is closed.
(Purpose: the threadLocal must be clean before returning to pool of
threadLocals of the container )
Any idea or way, thank you very much...