public void start() {
    if (stopped) {
      LOG.info("Starting ContainerPlacementStore");
      containerPlacementMessageStore.init();
      stopped = false;
    } else {
      LOG.warn("already started");
    }
  }
Perform startup operations. Method is idempotent.
samza-core/src/main/java/org/apache/samza/clustermanager/container/placement/ContainerPlacementMetadataStore.java