[HADOOP-14586] StringIndexOutOfBoundsException breaks org.apache.hadoop.util.Shell on 2.7.x with Java 9

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.7.2
• Fix Version/s: 2.7.4
• Component/s: common
• Labels: Java9

Environment

Java 9, build 175 (Java 9 release candidate as of June 25th, 2017)

• Target Version/s: 2.7.4
• Hadoop Flags: Reviewed
• Assignee: Akira Ajisaka
• Reporter: Uwe Schindler
• Created: 24/Jun/17 12:58
• Updated: 20/Aug/17 22:25
• Resolved: 11/Jul/17 23:06

Description

You cannot use any pre-Hadoop 2.8 component anymore with the latest release candidate build of Java 9, because it fails with an StringIndexOutOfBoundsException in org.apache.hadoop.util.Shell#<clinit>. This leads to a whole cascade of failing classes (next in chain is StringUtils).

The reason is that the release candidate build of Java 9 no longer has "-ea" in the version string and the system property "java.version" is now simply "9". This causes the following line to fail fatally:

  private static boolean IS_JAVA7_OR_ABOVE =
      System.getProperty("java.version").substring(0, 3).compareTo("1.7") >= 0;

Analysis:

• This code looks wrong, as comparing a version this way is incorrect.
• The substring(0, 3) is not needed, compareTo also works without it, although it is still an invalid way to compare a version.

Issue Links

• breaks: SOLR-10966 Add workaround for Hadoop-Common 2.7.2 incompatibility with Java 9
• breaks: SOLR-10951 Update Hadoop dependencies to 2.8.1, so Solr works with Java 9
• duplicates: HADOOP-10775 Shell operations to fail with meaningful errors on windows if winutils.exe not found
• is depended upon by: SOLR-11261 Update to Hadoop 2.7.4
• relates to: HADOOP-11123 Fix Java 9 incompatibilies in Hadoop