protected final void clean(){
  if (!isAlive())   return;
synchronized (this) {
    _shouldDie=true;
    notify();
  }
  try {
    join();
  }
 catch (  InterruptedException e) {
  }
  if (_expirationList != null)   _expirationList.clear();
}

protected final void clean ( ) { if ( ! isAlive ( ) ) return ; synchronized ( this ) { _shouldDie = true ; notify ( ) ; } try { join ( ) ; } catch ( InterruptedException e ) { } if ( _expirationList != null ) _expirationList . clear ( ) ; }
wakes up , waits for reaper to die , and clears all lease mappings .
