Processor support for select operations

Vitaly Davidovich vitalyd at
Tue Nov 11 19:27:30 UTC 2014

Don't mean to sidetrack this thread, but I really hope Unsafe can still be
obtained by non-JDK code in java 9.  Besides the effort required to move
existing code off it, there's also the need to then have "native" java code
performance match what Unsafe offers, which is a tall order since Unsafe
gets its performance advantage by dropping all the safety belts.
Therefore, I hope you guys don't fully lock it up and still allow access to
it.  It already has warning labels attached to it and given that java does
not provide language based "unsafe" regions, this is the only way to
achieve that.

On Tue, Nov 11, 2014 at 2:17 PM, John Rose <john.r.rose at> wrote:

> On Nov 11, 2014, at 11:00 AM, Vitaly Davidovich <vitalyd at> wrote:
> But in the meantime, just trying Unsafe to see what the perf benefit would
> be is still interesting, no?
> Yep.
> It's worth repeating:  Unsafe is only for internal use by the JDK.  The
> access restrictions on it,
> which are often circumvented, are going to be strengthened by the JDK 9
> module system,
> and the restrictions will become harder to circumvent.
> Use it for experiments if that's useful, but don't build it into your
> product.
> For more information, check out Paul Sandoz's talk on unsafe and
> varhandles at Java One 2014.
> — John
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the hotspot-compiler-dev mailing list