private void handleOnContainerStarted(ContainerId containerId) {
    String processorId = getPendingProcessorId(containerId);
    if (processorId != null) {
      log.info("Got start notification for Container ID: {} for Processor ID: {}", containerId, processorId);
      // 1. Move the processor from pending to running state
      final YarnContainer container = state.pendingProcessors.remove(processorId);

      state.runningProcessors.put(processorId, container);

      // 2. Invoke the success callback.
      SamzaResource resource = new SamzaResource(container.resource().getVirtualCores(),
          container.resource().getMemory(), container.nodeId().getHost(), containerId.toString());
      clusterManagerCallback.onStreamProcessorLaunchSuccess(resource);
    } else {
      log.warn("Did not find the Processor ID for the start notification for Container ID: {}. " +
          "Ignoring notification.", containerId);
    }
  }
Handles container started call back for a yarn container.
updates the YarnAppState's pendingProcessors and runningProcessors
and also invokes clusterManagerCallback.s stream processor launch success
@param containerId yarn container id which has started
samza-yarn/src/main/java/org/apache/samza/job/yarn/YarnClusterResourceManager.java