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https://issues.apache.org/jira/browse/HADOOP-14586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16062866#comment-16062866
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Steve Loughran commented on HADOOP-14586:
-----------------------------------------
This is the shell Java version probe in Hadoop 2.8.0:
{code}
/**
* query to see if system is Java 7 or later.
* Now that Hadoop requires Java 7 or later, this always returns true.
* @deprecated This call isn't needed any more: please remove uses of it.
* @return true, always.
*/
@Deprecated
public static boolean isJava7OrAbove() {
return true;
}
{code}
If this probe is the core problem, well, it can be cherry picked; along with
where the references have ll been cut. HADOOP-10775 was the patch, though it's
a bit big as it's trying to improve shell's failure handling. Marking as
related to that, though it could be a dupe/part-of.
> org.apache.hadoop.util.Shell causes failure in <clinit> on Java 9 RC build,
> leading to almost all of Hadoop failing (next one StringUtils)
> -------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-14586
> URL: https://issues.apache.org/jira/browse/HADOOP-14586
> Project: Hadoop Common
> Issue Type: Bug
> Components: common
> Affects Versions: 2.7.2
> Environment: Java 9, build 175 (Java 9 release candidate as of June
> 25th, 2017)
> Reporter: Uwe Schindler
> Assignee: Akira Ajisaka
> Priority: Blocker
> Labels: Java9, release-blocker
> Attachments: HADOOP-14586-branch-2.7-01.patch
>
>
> You cannot use any Hadoop 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:
> {code:java}
> private static boolean IS_JAVA7_OR_ABOVE =
> System.getProperty("java.version").substring(0, 3).compareTo("1.7") >=
> 0;
> {code}
> Analysis:
> - This code looks wrong, as comparing a version this way is incorrect.
> - The {{substring(0, 3)}} is completely useless, {{compareTo}} also works
> without it, although it is still an invalid way to compare a version.
> Maybe look at Lucene's source code (Constants.java) to have a better way in
> doing this! Sorry this is incredible to me! Hardcoding string bounds into a
> static initializer that are applied on a string that you have no control of...
> This issue breaks Apache Solr from working with Java 9, so I set it to
> "critical". We have to disable the whole Hadoop integration once Java 9 is
> detected.
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