@Override
  public long ramBytesUsed() {
    return INSTANCE_SIZE
        + downStreamChannelList.stream().map(ISink::ramBytesUsed).reduce(Long::sum).orElse(0L)
        + RamUsageEstimator.sizeOf(channelOpened)
        + RamUsageEstimator.sizeOf(hasSetNoMoreTsBlocks);
  }
max bytes this ShuffleSinkHandle can reserve.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/exchange/sink/ShuffleSinkHandle.java