New candidate JEP: 357: Migrate from Mercurial to Git

[David Lloyd]

Maybe it would be helpful to categorize the pros and cons as one-time
cost/benefit versus recurring cost/benefit?

On Mon, Jul 15, 2019 at 1:53 PM Aleksey Shipilev <shade at redhat.com> wrote:
>
> On 7/15/19 7:54 PM, mark.reinhold at oracle.com wrote:
> > https://openjdk.java.net/jeps/357
>
> Unfortunately, this JEP only discusses the advantages, and does not discuss the disadvantages of
> performing this move.
>
> The disadvantages, off the top of my head:
>  *) Conversion takes time and effort for all projects, including those developed outside of
> mainline: Amber, Loom, Panama, Portola, Shenandoah, Valhalla to name a few;
>  *) Developers who are already quite constrained to deliver things with 6 months pace would have to
> re-adjust their workflows, some would need re-training to Git, many would have to accept the
> temporary productivity losses, and/or modify their delivery schedules;
>  *) Downstream builders would need to refit their pipelines after the move -- and there are lots of
> them;
>
> Additionally, not addressed:
>  *) Existing hgupdater links in JBS would have to be updated, or they would break;
>  *) External links to hg.o.j.n -- that were deemed to be permalinks to the JDK source code, perhaps
> with lots of wishful thinking involved -- would break;
>  *) There are improvements to Mercurial that can make the conversion advantages less appealing. For
> example, clonebundles that I pointed out multiple times over the year (and Mark promised to deliver,
> at OpenJDK Committers Workshop in February 2019) is still not enabled:
> https://bugs.openjdk.java.net/browse/JDK-8211383. Instead, we have "Alternatives: Keep using
> Mercurial" (sic!).
>  *) The claim that "There are many more tools for interacting with Git than Mercurial" look dubious.
> For the tools I use from that list: IntelliJ, NetBeans, Atom are supporting Mercurial as well.
>
> AFAIU, JEPs are supposed to capture the pros and cons, and provide extended background for
> discussion for the changes that have wide area of effect. Alas, the JEP 357 does not look to be in
> that state at the moment.
>
> --
> Thanks,
> -Aleksey
>


-- 
- DML