RFR(XS): 8147844: new method j.l.Runtime.onSpinWait()

[Gil Tene]

> On Jan 27, 2016, at 9:41 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> HI Ivan,
> 
> On 27/01/2016 11:31 PM, Ivan Krylov wrote:
>> Hello,
>> 
>> Earlier there was a discussion on this mail alias about the spin loop
>> hint proposal [1]. Based on the feedback from that discussion some
>> changes were incorporated and the JEP has been filed [2]. There seems to
>> be a consensus on the API side. The JEP is now in a draft state and I
>> hope this JEP will get targeted for java 9 shortly.
> 
> The discussion in [1] continued in:
> 
> http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-December/037063.html
> 
> but ended abruptly. In particular Mark's query as to why this moved from Thread to Runtime was seemingly left unanswered.

The thread continued, but it looks like due to cross-posting with concurrency-interest and people replying on the thread dropping the cores-libs-dev recipient somehow. See continuations of the thread here: http://cs.oswego.edu/pipermail/concurrency-interest/2015-December/thread.html#14576 and here: http://cs.oswego.edu/pipermail/concurrency-interest/2015-December/thread.html#14580

Mark's question on why this was moved from Thread to Runtime is discussed in detail there. An easy summary in a single message body can be found here: http://cs.oswego.edu/pipermail/concurrency-interest/2015-December/014587.html . Also, Doug addressed questions about the brief/bland wording choice ("typically improve performance", which we then switched to "The runtime may may take action to improve the performance" at Brian's suggestion) here: http://cs.oswego.edu/pipermail/concurrency-interest/2015-December/014578.html

HTH.

> 
> Thanks,
> David
> 
>> Please review the upcoming API changes:
>> http://cr.openjdk.java.net/~ikrylov/8147844.jdk.00/
>> 
>> For the reference, the new generated JavaDoc for j.l.Runtime class and
>> the new method
>> http://ivankrylov.github.io/onspinwait/api/java/lang/Runtime.html#onSpinWait--
>> 
>> 
>> Thanks,
>> 
>> Ivan
>> 
>> 1 -
>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-October/thread.html#35613
>> 
>> 2 - https://bugs.openjdk.java.net/browse/JDK-8147832.