public synchronized boolean isWaiting() {
    switch (state) {
      case WAITING:
      case WAITING_TIMEOUT:
        return true;
      default:
        break;
    }
    return false;
  }
Returns true if the procedure is waiting for a child to finish or for an external event.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/Procedure.java