Re: High concurrency for master and high reading from slave slowing down insert

[Peter Brawley]

For huge Inserts on a system with lots of RAM and multiple cores, innodb_read_io_threads = 64 etc is worth a try. No guarantees.

The Java API may be a bottleneck. Have you tested its capacity? Remember that presorting bulk inserts on the PK does speed things up.

Bill Karwin's piece at https://www.slideshare.net/billkarwin/load-data-fast is a pretty good real-world summary of bulk insert benchmarking. You might want to rework someof his scripts for Java and see how they do on your system.

I doubt replication will help.