release-v2.4.8-20200729

2020-07-29 Alibaba Cloud.

    * version: 2.4.8
    * BUGFIX: fix bug that checkpoint.storage.db does not work since v2.4.6.
    * BUGFIX: fix bug of orphan document filter core. #389.
    * IMPROVE: remove listDatabase request when incr_sync.shard_key != auto.
    #385.
    * IMPROVE: add oplog_max_size and oplog_avg_size metric in restful: "repl/".
    * BUGFIX: fix bug of checkpoint duplicate updating when HA switch.
    * IMPROVE: increase syncer thread when fetching method is change stream.
    * IMPROVE: add readConcern and writeConcern in client to solve the
    orphan document problem reading from MongoS. #392
    * IMPROVE: fix wrong name usage in mongoshake-stat script, thanks @Neal
    Gosalia. #393.

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1. 修复2.4.6版本引入的，checkpoint db名字不为mongoshake无法正常运行的问题
2. 修复过滤孤儿文档出core的bug。 #389.
3. 在incr_sync.shard_key != auto去除listDatabase请求，减少对源mongodb的权限要求。#385.
4. 优化restful接口，添加oplog_max_size和oplog_avg_size的统计。
5. 修复HA切换后，备mongoshake仍旧刷checkpoint的bug。
6. change stream拉取下，增大解析的线程数（4->6）以提高性能。
7. 全量阶段过滤mongos上的孤儿文档。#392
8. 改进mongoshake-stat中的--help提示。#393