@Override
  public synchronized boolean isFinished() {
    for (ISink channel : downStreamChannelList) {
      if (!channel.isFinished()) {
        return false;
      }
    }
    return true;
  }
max bytes this ShuffleSinkHandle can reserve.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/exchange/sink/ShuffleSinkHandle.java