private void loadWALProps(TrimProperties properties) throws IOException {
    conf.setWalMode(
        WALMode.valueOf((properties.getProperty("wal_mode", conf.getWalMode().toString()))));

    int maxWalNodesNum =
        Integer.parseInt(
            properties.getProperty(
                "max_wal_nodes_num", Integer.toString(conf.getMaxWalNodesNum())));
    if (maxWalNodesNum > 0) {
      conf.setMaxWalNodesNum(maxWalNodesNum);
    }

    int walBufferSize =
        Integer.parseInt(
            properties.getProperty(
                "wal_buffer_size_in_byte", Integer.toString(conf.getWalBufferSize())));
    if (walBufferSize > 0) {
      conf.setWalBufferSize(walBufferSize);
    }

    boolean WALInsertNodeCacheShrinkClearEnabled =
        Boolean.parseBoolean(
            properties.getProperty(
                "wal_cache_shrink_clear_enabled",
                Boolean.toString(conf.getWALCacheShrinkClearEnabled())));
    if (conf.getWALCacheShrinkClearEnabled() != WALInsertNodeCacheShrinkClearEnabled) {
      conf.setWALCacheShrinkClearEnabled(WALInsertNodeCacheShrinkClearEnabled);
    }

    loadWALHotModifiedProps(properties);
  }
load a property file and set TsfileDBConfig variables.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/conf/IoTDBDescriptor.java