Clearing sessions when paster is down

[voltron]

For one reason or the other, the paster serve might be down,
maintenance, errors e.t.c. This would cause errors on the client if
certain pages depend on various session variables.Is there a hook,
callback that one can use to trigger an action when the server is
going down to clear out all the sessions? Polling in intervals to see
if the server is up might not be fast enough.

Thanks