Changes/Java8

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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

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 October 2014, 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 available.

Scratch and side-builds will be done (against OpenJDK 8) for most Java packages to spot any source incompatibilities earlier.

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.

Fedora 21 will probably End-of-life around early 2016 (around when F23 is released). OpenJDK 7 will publicly End-of-life in April 2015. 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 (Done)
    • Promote java-1.8.0-openjdk to a full java runtime status (Done)
    • In case of a mass rebuild, supply/apply patches to fix build against OpenJDK 8 (Done)
  • Other developers:
    • icedtea-web maintainers will need to update icedtea-web to run against OpenJDK 8 (Done)
    • Other java packagers will need to apply patches to their java package to ensure they can build against OpenJDK 8 (WIP)
    • Everyone will need to test packages to verify that they work against OpenJDK 8 (WIP)
  • Release engineering:
    • Remove java-1.7.0-openjdk from kickstarts, comps and so on (Done)
  • Policies and guidelines:
    • N/A

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.

Dependencies

The OpenJDK packages will need to be updated/removed:

  • java-1.7.0-openjdk
  • java-1.8.0-openjdk

OpenJDK 8 depends on various system libraries, but no new changes are required to other packages. In fact, a non-default version of java-1.8.0-openjdk is available on older Fedora releases too.

Contingency Plan

  • Contingency mechanism:
    • Leave OpenJDK 7 as the default Java SDK and runtime.
    • Ship OpenJDK 8 as a leaf package.
    • For packages that were rebuilt against OpenJDK 8, rebuild them against OpenJDK 7
  • Contingency deadline: 2014-08-01
  • Blocks release? No
  • Blocks product? TODO

Documentation

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.