Mercurial forests for JDK 8

[Alan Bateman]

Georges Saab wrote:
> If I have understood correctly the present system of the 'static and somewhat fixed schedule
> of integrations' was introduced a number of years ago when there were lots of issues with
> destabilizing (ok, build breaking!) changes coming in,  And that it has been successful in
> preventing these, albeit at quite a bit of cost.
>
> So what (other than momentum) is preventing us from having a more nimble integration
> capability?  In my naive view, it looks to be having better testing (as in more effective -- less but 
> more tailored to hit the issues in a particular integration repo). 
>
> I like Kelly's suggestion of viewing it as a 'budget of time' -- i.e. we should figure out the best set
> of tests for a repo that can be run within 24 hours'.  I think there is more that can be done here
> to make sure integration repos stay clean...
>
>   
Our processes are indeed legacy, and assume the worst.

Much of the lag between snapshot and integration today is due to 
pre-integration testing, the need and duration of which vary by area. In 
the core area at least, then we have to make efforts to reduce or 
eliminate this. For starters then it would be great if OpenJDK had build 
and test bots so that we have daily or continuous building and testing 
on all integration forest (and all platforms). Another one is that we 
need to put more effort into improving the robustness and through-put of 
our tests, meaning the tests in the jdk repository. The langtools area 
gets an A+ grade but the jdk repository gets a D- because we have many 
tests that having timing issues, are slow, or are just too sensitive to 
the environment. In my view, we have to fix these issues so that we get 
to the point where we can quickly see from the test results whether we 
are integration ready or not.  Bug verification and other work can happy 
lazily. I can't speak for the client and other areas but I will guess 
that not everything can be automated and that some level of special 
pre-integration testing will be required to be sure that regressions 
don't get into the master.

-Alan.