While implementing a solution for keeping warmed indexReaders around for our
various indexes (so users don't have to wait while we open an indexReader for
our one slow index), I've run into some serious problems trying to track down
all of the outstanding file handles to my indexes.
For a while
The FSDirectory does not itself hold any open files.
All that its close method actually does is disable future operations against it.
Still, it is a good practice to close it (after you've closed all IRs
and IWs) since this can help you catch bugs in your app (ie, if you
hit AlreadyClosedExceptio
