private final boolean shouldExpire() {
    return expirationNs != null && (System.nanoTime() - expirationNs) >= 0;
  }
Tries to expire and restart the session.
@param isAsync Whether the restart should happen asynchronously.
@return True if the session was, or will be restarted.
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/TezSessionPoolSession.java