Interview with Patrick Reinhart

Mercurial or Git as SCM for Java 12? “Git seems to be more tool-friendly than Mercurial at the moment”

Dominik Mohilo
© Shutterstock / MicroOne

Last month, the JDK team made a call for discussion in order to investigate a number of options for JDK source code management. But is it time to retire Mercurial in favor of Git? We talked to OpenJDK Author Patrick Reinhart about all this and more.

With Project Skara, the JDK team wishes to investigate alternatives for JDK source code management, that’s been using Mercurial repositories since 2008.

Is it a good idea to “retire” Mercurial and choose Git instead? Chime in with a vote and see what OpenJDK Author Patrick Reinhart has to say about this discussion.

What's the most beneficial alternative SCM and code review for the JDK source code?

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Don’t miss the interview with Stephen Colebourne about Project Skara:


JAXenter: Do you think moving the JDK from Mercurial to another Version Control System is a good idea?

Patrick Reinhart: From the perspective of a potential new committer, Git is definitely more popular these days. Not only from the tools perspective, but also if you take a look at all existing open source projects in general. On the other hand, the OpenJDK is not just some open source project like a lot of other ones out there.

JAXenter: What benefits would a move to another SCM -let’s say Git- have?

Patrick Reinhart: As I said before, for new contributors, Git seems to be more tool-friendly than Mercurial is at the moment. Nevertheless, the review process of the OpenJDK is a lot different than the ones for Github for example. The main part of a contribution takes place within one of the numerous mailing lists that exist. This part of the contribution is important as the actual SCM tool on its own.

JAXenter: What problems would such a move cause?

Patrick Reinhart: I guess it depends on what tool you seem to decide on in the end. If you take Git, for example, it could be hosted as “simple” as is done in the Linux world [it was actually built for that] which in the end, has nothing to do with the workflow as GitHub or others in that area do.

JAXenter: Is there any real alternative to Git as a replacement for Mercurial?

Patrick Reinhart: On the open source side, I do not see anything other than Git and maybe Subversion, in my opinion.

JAXenter: How about the Review Process? Should it stay in the mailing lists or should it also be changed?

Patrick Reinhart: The review process as it exists today, in general, seem to fit the needs. I could imagine that it could be improved at least tool-wise to lower the number of actual steps you have to take between different revisions of a code contribution. But to be clear, the most important part of a contribution does take place in the mailing lists anyway and this has a minor impact on the actual version control system.

Thank you!


Dominik Mohilo
Dominik Mohilo studied German and sociology at the Frankfurt University, and works at S&S Media since 2015.

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