void cleanUp(int threshold){
  if (idleLock.tryLock()) {
    try {
      drainTaskStack(threshold);
      evict(threshold);
    }
  finally {
      idleLock.unlock();
    }
  }
}

void cleanUp ( int threshold ) { if ( idleLock . tryLock ( ) ) { try { drainTaskStack ( threshold ) ; evict ( threshold ) ; } finally { idleLock . unlock ( ) ; } } }
performs any pending maintenance operations needed by the policy .
