private void doRetryWait(int retryNum) {
    try {
      if (retryNum < 3) {
        TimeUnit.MILLISECONDS.sleep(800L);
      } else if (retryNum < 5) {
        TimeUnit.MILLISECONDS.sleep(100L * (long) Math.pow(2, retryNum));
      } else {
        TimeUnit.MILLISECONDS.sleep(3200L);
      }
    } catch (InterruptedException e) {
      LOGGER.warn("Retry wait failed.", e);
      Thread.currentThread().interrupt();
    }
  }
Synchronously send RPC requests to DataNodes. See queryengine.thrift for more details.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/client/sync/SyncDataNodeClientPool.java