ByteBuffer performance issue in Java 9?

[Uwe Schindler]

Hi Andrew,

yes that was my impression, too.

Just for cross-checking: Mike, is it possible to also add a perf comparison between Java 8 and Java 9 when using SimpleFSDirectory or NIOFSDirectory (which are both FileChannel based since Java 7, the name is just backwards-compatibility)? If we see a slowdown there (maybe even larger) than it is not related to ByteBuffer positional/byte-wise reads and there is a general performance issue somewhere else.

> Right, but ByteBuffers were significantly rewritten for a significant
> performance *increase*.  Any slowdown shows that something has gone
> very wrong indeed.

That would be a pity, because of that we should check the above case with non-mmap based, conventional index access. As far as I remember: at the time when you announced the bytebuffer improvements we did some performance measurements and were impressed by the speedup. I think Robert Muir did something. Mike, do you know?

Maybe we should check with a Java 9 preview build from that time. I know that you can download older builds by changing the build number in the download URL.

Uwe