Any major performance change with I/O from JDK 6 that one should be aware of?

[Alan Bateman]

On 14/05/2012 12:05, Fabrizio Giudici wrote:
>
> I was going to ask you something similar, as after looking at the 
> sources of MappedByteBuffer I think there could be a 
> over-optimization. But I'm definitely not a HotSpot expert.
>
> Bingo. See console log below, in any case I'm getting now a similar 
> performance than Apple JDK 6 and I see disk reads in the system monitor.
>
>
> Since this seems to workaround the problem for my app, how can I 
> reliably set the .hotspot_compiler stuff? I mean, is there any -XX 
> option that can be used as well?
>
I see Tomas has replied pointing you to -XX:CompileCommand, that should 
work too.

The issue isn't actually a HotSpot issue, rather it's the loop that 
touches each page is essentially reduced to nothing when compiled, we 
will have to change it to prevent the compiler doing that.

-Alan.