Method CancelFromThreadPool

be/src/service/impala-server.cc:2268–2338

}

void ImpalaServer::CancelFromThreadPool(const CancellationWork& cancellation_work) {
  const TUniqueId& query_id = cancellation_work.query_id();
  QueryHandle query_handle;
  Status status = GetQueryHandle(query_id, &query_handle);
  // Query was already unregistered.
  if (!status.ok()) {
    VLOG_QUERY << "CancelFromThreadPool(): query " << PrintId(query_id)
               << " already unregistered.";
    return;
  }

  DebugActionNoFail(query_handle->query_options(), "QUERY_CANCELLATION_THREAD");
  Status error;
  switch (cancellation_work.cause()) {
    case CancellationWorkCause::TERMINATED_BY_SERVER:
    case CancellationWorkCause::GRACEFUL_SHUTDOWN:
      error = cancellation_work.error();
      break;
    case CancellationWorkCause::BACKEND_FAILED: {
      // We only want to proceed with cancellation if the backends are still in use for
      // the query.
      vector<NetworkAddressPB> active_backends;
      Coordinator* coord = query_handle->GetCoordinator();
      if (coord == nullptr) {
        // Query hasn't started yet - it still will run on all backends.
        active_backends = cancellation_work.failed_backends();
      } else {
        active_backends = coord->GetActiveBackends(cancellation_work.failed_backends());
      }
      if (active_backends.empty()) {
        VLOG_QUERY << "CancelFromThreadPool(): all failed backends already completed for "
                   << "query " << PrintId(query_id);
        return;
      }
      stringstream msg;
      for (int i = 0; i < active_backends.size(); ++i) {
        msg << active_backends[i];
        if (i + 1 != active_backends.size()) msg << ", ";
      }
      error = Status::Expected(TErrorCode::UNREACHABLE_IMPALADS, msg.str());
      break;
    }
    default:
      DCHECK(false) << static_cast<int>(cancellation_work.cause());
  }

  if (cancellation_work.unregister()) {
    UnregisterQueryDiscardResult(cancellation_work.query_id(), &error, true);
  } else {
    // Retry queries that would otherwise be cancelled due to an impalad leaving the
    // cluster. CancellationWorkCause::BACKEND_FAILED indicates that a backend running
    // the query was removed from the cluster membership due to a statestore heartbeat
    // timeout. Historically, this would cause the Coordinator to cancel all queries
    // running on that backend. Now, Impala attempts to retry the queries instead of
    // cancelling them.
    bool was_retried = false;
    if (cancellation_work.cause() == CancellationWorkCause::BACKEND_FAILED) {
      query_handle.query_driver()->TryQueryRetry(&*query_handle, &error, &was_retried);