[8u] RFR: Backport 8161993 G1 crashes if active_processor_count changes during startup

[David Holmes]

Hi Thomas,

On Mon Dec 19 15:25:42 UTC 2016 Thomas Schatzl wrote:
> On Fri, 2016-12-16 at 13:10 +1000, David Holmes wrote:
>> On 16/12/2016 1:06 PM, David Holmes wrote:
>> >
>> > Bug: https://bugs.openjdk.java.net/browse/JDK-8161993
>> >
>> > JDK9 changeset:
>> > http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/8986e5b85e73
>> >
>> > webrev: http://cr.openjdk.java.net/~dholmes/8161993/webrev.8u/
>> >
>> > The changes for 8147910 are there only for reference.
>> >
>> > The backport was straight-forward but couldn't apply directly due
>> > to
>> > file/directory renaming. Also in 9 we had already changed
>> > os::processor_count() to os::active_processor_count() and then to
>> > os::initial_active_processor_count(), but in 8u we skip the middle
>> > step.
>> Nope sorry - confused myself. In both cases we go from
>> processor_count()
>> to initial_active_processor_count(). So it's even more direct than I
>> thought.
>
>   this backport seems to contain both the changes from JDK-8147910
> and JDK-8161993.
> I am a bit confused what "The changes for 8147910 are there only for
> reference." means. Are you intending to push the webrev as is, or only
> the JDK-8161993 part?
> How would that work, as JDK-8161993 is based on JDK-8147910?
>
> If the former, I would prefer to make two separate backports, one for
> each. This makes it much easier to track whether a particular issue has
> already been backported or not (or is still missing).
> It does not seem to be that much more effort. I will review both asap.
>
> If this has been discussed before, and everyone agreed on that it is
> for some reason better to combine the backports, ignore this.

Both issues are of course being backported, so there is a changeset for 
each. The 8147910 backport applied cleanly and does not need a 
re-review. But I kept it in the webrev, as I said, so that you could 
refer to it for the API update.

I just need a statement that this is an accurate backport of 8161993.

Thanks,
David

> Thanks,
>   Thomas