private String getRunningProcessorId(String containerId) {
    for (Map.Entry<String, YarnContainer> entry : state.runningProcessors.entrySet()) {
      String key = entry.getKey();
      YarnContainer yarnContainer = entry.getValue();
      String yarnContainerId = yarnContainer.id().toString();
      if (yarnContainerId.equals(containerId)) {
        return key;
      }
    }
    return INVALID_PROCESSOR_ID;
  }
Given a containerId from Yarn (for example: containerId_app_12345, this method returns the processor ID
in the range [0,N-1] that maps to it.
@param containerId  the Yarn container ID.
@return  the Samza processor ID.
samza-yarn3/src/main/java/org/apache/samza/job/yarn/YarnClusterResourceManager.java