GCube Java 8 migration guide

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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.

NOTE

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

Running into one of them will require to refactor 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

PREREQUISITES

.......

Source Code - UNDER CONSTRUCTION

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

Behaviour Incompatibilities - TO COMPLETE

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

Other Incompatibilities - TO COMPLETE

" 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 proposed was

  • 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.

JVM

JVM memory management changed in Java 8: concept of PermGen space has been replaced by Metaspace.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.

TODO: not enough results to provide guidelines and instructions


References

  • Oracle releases plan

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

  • 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/

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