apache/tajo — pull request #139 by hyunsik (2014-09-14 13:09:25+00:00)
Title: TAJO-1024: RpcConnectionPool::getConnection can cause NPE at initialization

It's concurrency bug. So, it is hard to reproduce the case. So, I omitted the unit tests. But, it definitely fixes the bug. After I apply it, I couldn't see the bug again. @jinossy helped this work.