[SPARK-1437] Jenkins should build with Java 6

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Implemented
• Affects Version/s: 0.9.0
• Component/s: Build, Project Infra
• Labels: javac jenkins
• Assignee: Shane Knapp
• Reporter: Sean R. Owen
• Created: 07/Apr/14 22:01
• Updated: 06/May/15 17:39
• Resolved: 04/May/15 18:17

Description

Apologies if this was already on someone's to-do list, but I wanted to track this, as it bit two commits in the last few weeks.

Spark is intended to work with Java 6, and so compiles with source/target 1.6. Java 7 can correctly enforce Java 6 language rules and emit Java 6 bytecode. However, unless otherwise configured with -bootclasspath, javac will use its own (Java 7) library classes. This means code that uses classes in Java 7 will be allowed to compile, but the result will fail when run on Java 6.

This is why you get warnings like ...

Using /usr/java/jdk1.7.0_51 as default JAVA_HOME.
...
[warn] warning: [options] bootstrap class path not set in conjunction with -source 1.6

The solution is just to tell Jenkins to use Java 6. This may be stating the obvious, but it should just be a setting under "Configure" for SparkPullRequestBuilder. In our Jenkinses, JDK 6/7/8 are set up; if it's not an option already I'm guessing it's not too hard to get Java 6 configured on the Amplab machines.