I'm working on HBASE-21512, where I want to rebuild the sync client based on the async client, so I need to support all the features of sync client in async client.
And there is a 'Preemptive Fast Fail' feature which was introduced in HBASE-12075, and the implementation is deeply tied with the rpc retrying framework of sync client, which makes it a bit difficult to be implemented in async client. What's more, I think the problem here is almost the same with HBASE-16388, that we do not want a slow or broken region server to hang all the client threads. I think we can mark it as deprecated on branch-2, and remove it on master. Just let users use the feature introduced in HBASE-16388 instead. Suggestions are welcomed. Thanks.
