@SuppressWarnings("unsafeThreadSchedule")
  public static ScheduledFuture<?> submitAutoCommitWorker(
      final Runnable task, final long autoCommitIntervalMs) {
    UPSTREAM_DATA_FLOW_EXECUTOR.launchIfNeeded();
    return UPSTREAM_DATA_FLOW_EXECUTOR.scheduleWithFixedDelay(
        task,
        generateRandomInitialDelayMs(autoCommitIntervalMs),
        autoCommitIntervalMs,
        TimeUnit.MILLISECONDS);
  }
Downstream Data Flow Executor: execute poll task
iotdb-client/session/src/main/java/org/apache/iotdb/session/subscription/consumer/base/SubscriptionExecutorServiceManager.java