@Override
  public void releaseLocks(List<HiveLock> hiveLocks) {
    LOG.info("releaseLocks: " + hiveLocks);
    for (HiveLock lock : hiveLocks) {
      try {
        unlock(lock);
      } catch (LockException e) {
        // Not sure why this method doesn't throw any exceptions,
        // but since the interface doesn't allow it we'll just swallow them and
        // move on.
        //This OK-ish since releaseLocks() is only called for RO/AC queries; it
        //would be really bad to eat exceptions here for write operations
      }
    }
  }
Used to make another attempt to acquire a lock (in Waiting state)
@param extLockId
@return result of the attempt
@throws LockException
ql/src/java/org/apache/hadoop/hive/ql/lockmgr/DbLockManager.java