@Override
  public void run() {
    // if a cancel thread has already entered this executor, we have not reason to continue.
    if (!hasCloseoutThread.compareAndSet(false, true)) {
      return;
    }

    final Thread myThread = Thread.currentThread();
    myThreadRef.set(myThread);
    final String originalThreadName = myThread.getName();
    final FragmentHandle fragmentHandle = fragmentContext.getHandle();
    final DrillbitContext drillbitContext = fragmentContext.getDrillbitContext();
    final ClusterCoordinator clusterCoordinator = drillbitContext.getClusterCoordinator();
    final DrillbitStatusListener drillbitStatusListener = new FragmentDrillbitStatusListener();
    final String newThreadName = QueryIdHelper.getExecutorThreadName(fragmentHandle);

    try {

      myThread.setName(newThreadName);

      // if we didn't get the root operator when the executor was created, create it now.
      final FragmentRoot rootOperator =
          this.rootOperator != null
              ? this.rootOperator
              : drillbitContext.getPlanReader().readFragmentOperator(fragment.getFragmentJson());

      root = ImplCreator.getExec(fragmentContext, rootOperator);
      if (root == null) {
        return;
      }

      clusterCoordinator.addDrillbitStatusListener(drillbitStatusListener);
      updateState(FragmentState.RUNNING);

      acceptExternalEvents.countDown();
      injector.injectPause(fragmentContext.getExecutionControls(), "fragment-running", logger);

      final DrillbitEndpoint endpoint = drillbitContext.getEndpoint();
      logger.debug(
          "Starting fragment {}:{} on {}:{}",
          fragmentHandle.getMajorFragmentId(),
          fragmentHandle.getMinorFragmentId(),
          endpoint.getAddress(),
          endpoint.getUserPort());

      final UserGroupInformation queryUserUgi =
          fragmentContext.isImpersonationEnabled()
              ? ImpersonationUtil.createProxyUgi(fragmentContext.getQueryUserName())
              : ImpersonationUtil.getProcessUserUGI();

      queryUserUgi.doAs(
          new PrivilegedExceptionAction<Void>() {
            public Void run() throws Exception {
              injector.injectChecked(
                  fragmentContext.getExecutionControls(), "fragment-execution", IOException.class);
              /*
               * Run the query until root.next returns false OR we no longer need to continue.
               */
              while (shouldContinue() && root.next()) {
                // loop
              }

              return null;
            }
          });

    } catch (OutOfMemoryError | OutOfMemoryException e) {
      if (!(e instanceof OutOfMemoryError) || "Direct buffer memory".equals(e.getMessage())) {
        fail(UserException.memoryError(e).build(logger));
      } else {
        // we have a heap out of memory error. The JVM in unstable, exit.
        CatastrophicFailure.exit(
            e, "Unable to handle out of memory condition in FragmentExecutor.", -2);
      }
    } catch (AssertionError | Exception e) {
      fail(e);
    } finally {

      // no longer allow this thread to be interrupted. We synchronize here to make sure that cancel
      // can't set an
      // interruption after we have moved beyond this block.
      synchronized (myThreadRef) {
        myThreadRef.set(null);
        Thread.interrupted();
      }

      // We need to sure we countDown at least once. We'll do it here to guarantee that.
      acceptExternalEvents.countDown();

      // here we could be in FAILED, RUNNING, or CANCELLATION_REQUESTED
      cleanup(FragmentState.FINISHED);

      clusterCoordinator.removeDrillbitStatusListener(drillbitStatusListener);

      myThread.setName(originalThreadName);
    }
  }
 /**
  * Resume all the pauses within the current context. Note that this method will be called from
  * threads *other* than the one running this runnable(). Also, this method can be called multiple
  * times.
  */
 public synchronized void unpause() {
   fragmentContext.getExecutionControls().unpauseAll();
 }