List<ProcessorNode> getAllProcessorNodes() {
    List<String> processorZNodes = getSortedActiveProcessorsZnodes();
    LOG.debug("Active ProcessorZNodes in zookeeper: {}.", processorZNodes);
    List<ProcessorNode> processorNodes = new ArrayList<>();
    for (String processorZNode: processorZNodes) {
      String ephemeralProcessorPath = String.format("%s/%s", keyBuilder.getProcessorsPath(), processorZNode);
      String data = readProcessorData(ephemeralProcessorPath);
      if (data != null) {
        processorNodes.add(new ProcessorNode(new ProcessorData(data), ephemeralProcessorPath));
      }
    }
    return processorNodes;
  }
Fetches all the ephemeral processor nodes of a standalone job from zookeeper.
@return a list of {@link ProcessorNode}, where each ProcessorNode represents a registered stream processor.
samza-core/src/main/java/org/apache/samza/zk/ZkUtils.java