Changes/Java8

Java 8

Summary

Make Java 8 (provided by OpenJDK 8 which is java-1.8.0-openjdk) the default Java runtime. The current default Java runtime (Java 7, provided by OpenJDK 7, java-1.7.0-openjdk) will be obsoleted and removed.

This is essentially an upgrade to the latest Java and OpenJDK version.

Owner

• Name: Omair Majid
• Email: omajid@redhat.com
• Release notes owner:

Current status

• Targeted release: Fedora 21
• Last updated: 2014-03-19
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

The current default Java 7 runtime in Fedora is OpenJDK 7. The latest version of OpenJDK, 8, was released on 18 March 2014. Given that Fedora 21 will not be released before August, it makes sense to include the latest version of OpenJDK in Fedora 21.

OpenJDK 8 is a significant update to Java. It brings in significant new features to the Java language, including lambdas, a new javascript engine and lots of new library features. A complete list of features is available.

OpenJDK 8 is a backwards compatible update. Theoretically everything that worked against OpenJDK 7 should continue working against OpenJDK 8. There are a few exceptions:

• OpenJDK8 is much more strict when it comes to building javadocs. Many -javadoc package in Fedora fail to build. Those that are built should continue working just fine.
• Packages that rely on non-public OpenJDK API may fail to build/run.

A complete list of incompatibilities is avilable. The incompatibilities are source and behavioural only.

It may be a good idea to mass rebuild Java packages against OpenJDK 8 to spot any source compatiblities earlier. This is not required.

Benefit to Fedora

Shipping the latest version of OpenJDK works towards the Fedora goal of "First". OpenJDK 8 brings significant new features to the Java language and libraries and platform. Soon, programmers will want to use these Java features and Fedora should provide them. Sooner or later, upstream projects will start to require Java 8.

If what happended with OpenJDK 6 is going to repeat, then development of OpenJDK 7 will stop before (or just around the time) Fedora 21 is End-of-Life'ed and security patches may not be backported to OpenJDK 7 (or if they are, they will be significantly delayed). If Fedora 21 ships with OpenJDK 7, this will leave users vulnerable to exploits.

Scope

• Proposal owners:
  • Deprecate/Obsolete java-1.7.0-openjdk
  • Promote java-1.8.0-openjdk to a full java runtime status (fix provides in package)
  • In case of a mass rebuild, supply/apply patches to fix build against OpenJDK 8

• Other developers:
  • icedtea-web maintainers will need to update icedtea-web to run against OpenJDK 8
  • Other java packagers will need to apply patches to their java package to ensure they can build against OpenJDK 8
  • Everyone will need to test packages to verify that they work against OpenJDK 8

• Release engineering:
  • Remove java-1.7.0-openjdk
  • Possibly mass-rebuild (?) all Java packages. This is not strictly required to make OpenJDK 8 the default Java runtime.

• Policies and guidelines:
  • Many -javadoc packages fail to build. The OpenJDK 8 maintainers and the Java SIG are working on identifying a solution. The solution may require guideline changes making -javadoc subpackages optional.

Upgrade/compatibility impact

Upgrades from previous Fedora versions should be seamless. java-1.8.0-openjdk will replace (Obsoletes and Provides) java-1.7.0-openjdk.

OpenJDK 8 is a backwards compatible update. Code that worked against OpenJDK 7 should continue to run against OpenJDK 8. Code compiled against OpenJDK 8 will not run against OpenJDK 7 by default (separate compiler flags are needed to generate OpenJDK 7-compatible bytecode).

Customizations of OpenJDK 7 will be lost with an update to OpenJDK 8.

How To Test

This is a software only change. The results should be consistent across all architectures (i686, x86_64, armv7, aarch64) and hardware.

0. What special hardware / data / etc. is needed (if any)? Answer: None

1. How do I prepare my system to test this change? What packages need to be installed, config files edited, etc.? Answer: Install any Java package (ant,maven, eclipse are good candidates).

2. What specific actions do I perform to check that the change is working like it's supposed to? Answer: Run the java package you installed in step 1.

3. What are the expected results of those actions? Answer: java-1.8.0-openjdk (or java-1.8.0-openjdk-headless) should be installed as a dependency. The Java application you installed should work like it does normally.

User Experience

This change to the Java runtime should be mostly invisible to a user.

Java developers will notice that a newer version of Java is packaged. Java applications will run on top of the latest Java runtime.

Contingency Plan

• Contingency mechanism:
  • Leave OpenJDK 7 as the default Java SDK and runtime.
  • Ship OpenJDK 8 as a leaf package.
  • *If* a mass rebuild was done, rebuild Java packages against OpenJDK 7
• Contingency deadline: 2014-08-01
• Blocks release? No
• Blocks product? TODO

Documentation

• Java 8 Release Notes. Please note that these release notes refer to a few proprietary components (including JavaFX, Deployment, Java DB and Java Mission Control) that are not included in Fedora packages.
• OpenJDK 8 Features
• Deveopment timeline

Release Notes

• Java 8 Release notes
• User customizations made to java-1.7.0-openjdk (specifically, to files under /usr/lib/jvm/java-1.7.0*/*) will not be carried across to java-1.8.0-openjdk.