Now master and regionserver use zk to coordinate log split tasks. The split log manager manages all log files which need to be scanned and split. Then the split log manager places all the logs into the ZooKeeper splitWAL node (/hbase/splitWAL) as tasks and monitors these task nodes and waits for them to be processed. Each regionserver watch splitWAL znode and grab task when node children changed. And regionserver does the work to split the logs.
Open this umbrella issue to move this "coordinate" work to use new procedure v2 framework and reduce zk depencency. Plan to finish this before 3.0 release. Any suggestions are welcomed. Thanks.