Hi It seems to me that some NIO based file creates don't scale work well with REFS formatted drives REFS is an alternative (to NTFS) drive format for Windows 8 and above
When working with NTFS on my test system, as we use more threads the performance improves so some degree, (1000 files creates take 5-600 ms with one thread and 2-300 ms with 4 threads) when using REFS the single threaded times are roughly the same for 1 and 2 threads, but get much worse for 3 and 4 threads (1200 - 1600 ms) this showdown is only when using FileChanel.open and synchronous IO, for the AsynchronousFileChannel it seems roughly the to scale as expected CSV attached for the test results, and some test code. The test code is in scala, and I can convert if needed, but it just really 3 calls, to open write and close the files My test system is an I7 4 core window 10 pro with Norton installed, but an exclusion for the specified drives, and indexing disabled. All writes are to an M.2 SSD with write-though cache Some background I am working on the back end code generation of the scala compiler which generates many thousand small .class files, and part of that is to tune the IO. For windows where the IO cost is significant, so I had a few test app to simulate and measure the relative performance of the different alternatives Any ideas for a bulk file creation alternative welcome. I know we could write to a JAR but that requires other re-tooling Regards Mike
