java nio select() advantage but comparison keys - why?

in minute exam formula i have found selector.select() relapse but selector.selectedkeys() containing any keys process. duty avaricious loop i register an accept()ed channel with

selectionkey.op_read | selectionkey.op_connect

as operations interest.

according docs, select() should relapse when:

1) there channels acted upon.

2) definitely selector.wakeup() - keys selected.

3) definitely thread.interrupt() thread doing select() - keys selected.

if i keys after select() i contingency cases (2) (3). however, formula job wakeup() interrupt() trigger returns.

any ideas causing behaviour?