First，we do the test between local-master-splitting and distributed-log-splitting
Environment：34 hlog files, 5 regionservers,(after kill one, only 4 rs do ths splitting work), 400 regions in one hlog file
In fact, in our production environment, distributed-log-splitting also took 60s with 30 regionservers for 34 hlog files (regionserver may be in high load)
We found split-worker split one log file took about 20s
(30ms~50ms per writer.close(); 10ms per create writers )
I think we could do the improvement for this:
Parallelizing the create and close writers in threads
In the patch, change the logic for distributed-log-splitting same as the local-master-splitting and parallelizing the close in threads.