Revision as of 10:26, 17 February 2017

This page collects the guidelines for the migration of D4Science infrastructure and the gCUbe software from Java 7 to Java 8. It also collects common issues (and their solution) experienced during the migration as reference for all gCube developers.

There are (few) documented incompatibilities between Java 7 and Java 8.

Running into one of them will require to re-factor the component and release a new version of it.

Java 8 compatibility guide: http://www.oracle.com/technetwork/java/javase/8-compatibility-guide-2156366.html

Source Code

Source Incompatibilities - TO COMPLETE

• Detected at integration time (the component does not build)
• animal-sniffer-maven-plugin can be used by developers to detect them at development time

Dependencies

Some third-party libraries are not compiled in Java 8 and their code is not Java 8 compatible. This is usually the case of very old versions.

• lombok
  • not compatible: 0.11.6
  • suggested: 1.14.8

Behaviour Incompatibilities - TO COMPLETE

• Cannot be detected at development and integration time
• We will need to carefully test our artifacts

Other Incompatibilities - TO COMPLETE

1. TOMCAT incopatibilities

Java8 required as pre-requisited the latest TOMCAT version as reported in the https://support.d4science.org/issues/6306: "Moving to the latest tomcat version is not so easy. We want to stuck with the distribution provided tomcat for a lot of reasons:

• backport of bug and security fixes
• compatibility with the apr libraries
• In addition to that, the javassist exceptions were a cosmetic only problem in the past, and an upgrade to a newer version of javassist was planned.

" The solution is :

• for gCore : updating the xerces and xml-api libraries to make the gCore services working;
• for Smartgears: upgrade on ubuntu 14.04 all the development and production infrastructure. This should be resolved the problems manifested for the javassist and xml parsing.

Due to the split of the release in gCore and Smartgear components the migration and possible resolution of the issue are provided both.

JVM - TO COMPLETE

JVM memory management changed in Java 8: concept of PermGen space has been replaced by Metaspace. As consequence, startup options used in Java 7 (e.g. "-XX:MaxPermSize") rae not valid anymore in JVM 8.

*node12-d-d4s.d4science.org (it'll replace node13.d.d4science.research-infrastructures.eu)
*node13-d-d4s.d4science.org (it'll replace node15.d.d4science.research-infrastructures.eu)
*node14-d-d4s.d4science.org (it'll replace node20.d.d4science.research-infrastructures.eu)

References

• Oracle releases plan

http://www.oracle.com/technetwork/java/eol-135779.html

• New features in Java 8
  • http://www.oracle.com/technetwork/java/javase/8-whats-new-2157071.html
  • https://leanpub.com/whatsnewinjava8/read

• Compatibility guide

http://www.oracle.com/technetwork/java/javase/8-compatibility-guide-2156366.html

• Animal Sniffer Plugin Guide

https://blog.gvsig.org/2011/07/25/hunting-api-incompatibilities-with-the-animal-sniffer-project/