Wheezy LTS and the switch to OpenJDK 7Sun 19 June 2016 by Markus Koschany
Wheezy's LTS period started a few weeks ago and the LTS team had to make an early support decision concerning the Java eco-system since Wheezy ships two Java runtime environments OpenJDK 6 and OpenJDK 7. (To be fair, there are actually three but gcj has been superseded by OpenJDK a long time ago and the latter should be preferred whenever possible.)
OpenJDK 6 is currently maintained by Red Hat and we mostly rely on their upstream work as well as on package updates from Debian's maintainer Matthias Klose and Tiago Stürmer Daitx from Ubuntu. We already knew that both intend to support OpenJDK 6 until April 2017 when Ubuntu 12.04 will reach its end-of-life. Thus we had basically two options, supporting OpenJDK 6 for another twelve months or dropping support right from the start. One of my first steps was to ask for feedback and advice on debian-java since supporting only one JDK seemed to be the more reasonable solution. We agreed on warning users via various channels about the intended change, especially about possible incompatibilities with OpenJDK 7. Even Andrew Haley, OpenJDK 6 project lead, participated in the discussion and confirmed that, while still supported, OpenJDK 6 security releases are "always the last in the queue when there is urgent work to be done".
Eventually we decided to concentrate our efforts on OpenJDK 7 because we are confident that for the majority of our users one Java implementation is sufficient during a stable release cycle. An immediate positive effect in making OpenJDK 7 the default is that resources can be relocated to more pressing issues. On the other hand we were also forced to make compromises. The switch to a newer default implementation usually triggers a major transition with dozens of FTBFS bugs and the OpenJDK 7 transition was no exception. I pondered about the usefulness of fixing all these bugs for Wheezy LTS again and focussing on runtime issues instead and finally decided that the latter was both more reasonable and more economic.
Different from regular default Java changes, users will still be able to use OpenJDK 6 to compile their packages and the security impact for development systems is in general neglectable. More important was to avoid runtime installations of OpenJDK 6. I identified eighteen packages that strictly depended on the now obsolete JRE and fixed those issues on 4 May 2016 together with an update of java-common and announced the switch to OpenJDK 7 with a Debian NEWS file.
If you are not a regular reader of Debian news and also not subscribed to debian-lts, debian-lts-announce or debian-java, remember 26 June 2016 is the day when OpenJDK 7 will be made the default Java implementation in Wheezy LTS. Of course there is no need to wait. You can switch right now:
sudo update-alternatives --config java