触发 CheckPoint（合并）的2种条件是：
1、当Edits的日志条数达到一定的数量的时候（100w条）
2、当到了一定的时间(3600s)，但是Edits的日志条数还未达到指定的数量
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其中这2个值都是可以进行修改的，hdfs-core.xml
时间
| dfs.namenode.checkpoint.period | 3600s | The number of seconds between two periodic checkpoints. Support multiple time unit suffix(case insensitive), as described in dfs.heartbeat.interval. |
日志条数
| 1000000 | The Secondary NameNode or CheckpointNode will create a checkpoint of the namespace every 'dfs.namenode.checkpoint.txns' transactions, regardless of whether 'dfs.namenode.checkpoint.period' has expired. |
修改这2个参数即可修改成你想要的数值
参考链接：
https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml