Spin Loop Hint support: Draft JEP proposal

Gil Tene gil at azulsystems.com
Tue Oct 6 14:04:54 UTC 2015

Sent from Gil's iPhone

> On Oct 6, 2015, at 1:16 AM, Andrew Haley <aph at redhat.com> wrote:
>> On 06/10/15 05:32, Gil Tene wrote:
>> I don't think of this as platform specific. And it's not much lower
>> level than e.g. some java.util.concurrent stuff (but probably
>> doesn't belong in that package because it's not really about
>> concurrency). I'm looking for a proper Java SE spec'ed way to do
>> this. So sun.misc.* won't work. I'm sure we don't want another
>> Unsafe for people to abuse...
>> But naming the class and method is the smaller, easier detail. Right? ;-)
> Sure.  I would have thought, though, that java.util.concurrent was a
> natural home for this.  Is there any kind of userland spinlock which
> is not about concurrency?

The same can be asked about Thread.notify().

To me, spinKoopHint() fits in (as in "probably a method in the same class") with other performance-oriented hints. Like prefetch variants (which we don't have but also probably need. E.g. prefetchWithIntentToWrite()). And placing prefetch hints in j.u.c would not make much sense.

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