Merging jdk9/hs-rt with jdk9/hs

[Alejandro Murillo]

Hi Mikael,
I apologize I missed your original email. Just seeing this now.

You don't mention the plans about gate-keeping,
will the hs-rt gatekeeper will also also assume the
synching with dev,  and therefore the submission of PIT,  etc?

If not, since main will be constantly changing, I will need
to be provided with the tips of a stable snapshot to merge with dev to 
run pit.
And then a hint of when to push the merge back to main.
Since we have to push with JPRT,  there are some situations for 
potential problems here.

Of course, that's not different to what is currently done to merge 
jdk9/dev to master,
except that we now have mach5 to pin point stable jdk9/dev snapshots,
and also,  there's nothing coming back from master to dev weekly
(except tags) and once in a while special integrations.
And as mentioned above, with hs repos, we use JPRT to push

Thanks
Alejandro


On 4/6/2016 4:19 PM, Mikael Vidstedt wrote:
>
> Having heard no feedback[1], we're going to go ahead with this 
> experiment and the plan is to do the switch next week, *Friday April 
> 15th*. Again, please note that any outstanding work based on 
> jdk9/hs-rt will have to be rebased on jdk9/hs once the switch is made. 
> More information as we get closer to the actual switchover.
>
> Let us know if you have any concerns with the date, and/or any 
> feedback on how it's working out.
>
> Cheers,
> Mikael
>
> [1] Not even from Volker *hint* ;)
>
> On 3/21/2016 4:59 PM, Mikael Vidstedt wrote:
>>
>> All,
>>
>> The JDK 9 development of Hotspot is primarily done in two different 
>> mercurial forests: jdk9/hs-rt[1], and jdk9/hs-comp[2]. In June of 
>> last year we moved[3] all the GC development from jdk9/hs-gc[4] to 
>> jdk9/hs-rt, and the experience so far has been a good one. Change 
>> propagation (from jdk9/hs-rt to jdk9/hs-gc and vice verse) is now a 
>> non-issue, we get testing faster on the union of the changes where 
>> previously it could take weeks to catch a GC related bug in RT 
>> testing, etc.
>>
>> However, both jdk9/hs-rt and jdk9/hs-comp still integrate through a 
>> third forest - jdk9/hs[5], aka. hs "main" - before the changes are 
>> integrated to jdk9/dev[6]. In line with the previous simplification, 
>> we would like to suggest a further simplification of the forest 
>> structure. Specifically, we suggest that the work currently done on 
>> the jdk9/hs-rt forest moves directly to the jdk9/hs forest. In 
>> addition to making the forest structure easier to understand, this 
>> would have the benefit of removing one set of integrations (jdk9/hs 
>> <-> jdk9/hs-rt), which further reduces cost and propagation time. It 
>> is also paving the way for eventually integrating up to jdk9/dev more 
>> often (but that is a separate discussion).
>>
>> We suggest that the experiment starts on April 15th, and goes on for 
>> at least two weeks (giving us some time to adapt in case of issues). 
>> Monitoring and evaluation of the new structure will take place 
>> continuously, with an option to revert back if things do not work 
>> out. The experiment would keep going for at least a few months, after 
>> which we will evaluate it and depending on the results consider 
>> making it the new standard. If so, the jdk9/hs-rt forest will 
>> eventually be retired, with an option of looking at further reduction 
>> of forests going forward. At least for now, we suggest that 
>> jdk9/hs-comp remains a separate forest and that it integrates through 
>> jdk9/hs just like it does today.
>>
>> Much like when we merged the jdk9/hs-gc and jdk9/hs-rt forests we 
>> would leave the jdk9/hs-rt forest around until we see if the 
>> experiment works out. We would also lock it down so that no 
>> accidental integrations are made to it. Once the jdk9/hs-rt forest is 
>> locked down, any work in flight based on it would have to be rebased 
>> on jdk9/hs.
>>
>> Please let us know if you have any feedback or questions!
>>
>> Cheers,
>> Mikael
>>
>> [1]http://hg.openjdk.java.net/jdk9/hs-rt
>> [2]http://hg.openjdk.java.net/jdk9/hs-comp
>> [3]http://mail.openjdk.java.net/pipermail/hotspot-dev/2015-May/thread.html 
>>
>> [4]http://hg.openjdk.java.net/jdk9/hs-gc
>> [5]http://hg.openjdk.java.net/jdk9/hs
>> [6]http://hg.openjdk.java.net/jdk9/dev
>>
>

-- 
Alejandro