public void runSequential() {
    int exitVal = -101;
    try {
      exitVal = tsk.executeTask(ss == null ? null : ss.getHiveHistory());
    } catch (Throwable t) {
      if (tsk.getException() == null) {
        tsk.setException(t);
      }
      LOG.error("Error in executeTask", t);
    }
    if (tsk.getException() != null) {
      result.setTaskError(tsk.getException());
    }
    result.setExitVal(exitVal);
    taskQueue.releaseRunnable();
  }
Launches a task, and sets its exit value in the result variable.
ql/src/java/org/apache/hadoop/hive/ql/exec/TaskRunner.java