@Override
  protected void runOneIteration() throws Exception {
    Map<String, Cluster> clusterMap = m_clustersProvider.get().getClusters();
    for (Cluster cluster : clusterMap.values()) {
      try {
        LOG.debug("Analyzing tasks for cluster {} that can be retried during Stack Upgrade.", cluster.getClusterName());
        Long effectiveRequestId = getActiveUpgradeRequestId(cluster);
        if (effectiveRequestId != null) {
          LOG.debug("Upgrade is in-progress with request id {}.", effectiveRequestId);
          retryHoldingCommandsInRequest(effectiveRequestId);
        }
      } catch (Exception e) {
        LOG.error("Unable to analyze commands that may be retried for cluster with id {}. Exception: {}",
            cluster.getClusterId(), e.getMessage());
      }
    }
  }
{@inheritDoc}
<p/>
Analyze each cluster for any active upgrades and attempt to retry any actions in a HOLDING_* status.
ambari-server/src/main/java/org/apache/ambari/server/state/services/RetryUpgradeActionService.java