[takoi]

Well, XBMC grants a grace time of 5 seconds for addons to shut down themselfs cleanly. If they do not manage to do that within time XBMC just kills the thread which CAN result in unclosed handles etc. So I think XBMC does classify that as an issue which is indicated by the loglevel "ERROR" which you can see in the log.
Also I think those 5 seconds grace period are setup for each addon individually. Meaning if you have for example 5 of such addons which do not close correctly XBMC will hang for 25 seconds before shutting down.

First of all: this only applies to network locations. Anything local should exit well within 5 seconds so there will not be any 'unclosed handles' since everything else goes through xbmcvfs. Patches welcome but I think there is not much hope for being able to terminate the network polling in less than 5 seconds for multiple reasons. One being that a single call to xbmcvfs may take several seconds. And it will not interupt any calls until the 5 seconds have passed. Now you're already out of time..