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https://issues.apache.org/jira/browse/HADOOP-14586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16066388#comment-16066388
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Uwe Schindler commented on HADOOP-14586:
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Hi,
Thanks [~ste...@apache.org] - this is the problem we had. We do not install
Hadoop anywhere or we run Solr inside Apache Solr, we are just users using the
client library (and parts of its tests, e.g. the MiniDFSCluster for testing -
which works on Java 9). The used client library has a bug that breaks a
component that uses it. So - as said before, I'd not backport anything complex,
I'd just apply the bugfix simple patch that changes the static constant to
"true" and all should be happy. There is no risk at all, as Hadoop 2.7 has a
minimum requirement of Java 7, so the constant is "true".
As users of the hadoop client library: We just don't want to break our "Java 9
compatible" Solr Core that uses the Hadoop libraries for some authentication
stuff and allows to store indexes on HDFS. Another problem why we don't
necessarily want to upgrade Hadoop in stable Solr (6.x), because how behaves a
newer Hadoop client when talking to an older version. So we can't just raise
version number.
We don't tell our users that you can use Solr with Hadoop on Java 9, but Solr
on its own should run with Java 9 and dependent libraries should not fail on
classloading. So we have two possibilities:
- Remove all of hadoop support from Solr Core (not a good idea)
- Just fix the "Shell" class with a one-liner so it can actually just "load"
successfully on Java 9 and not break other stuff (like StringUtils, Kerberos
Auth,...). One possibility to do this is to fork hadoop-common in github and
ship Solr with a patched version. But I don't like to do this!
So I would really hope that you could apply the simple one-liner patch! Thanks
:-)
> org.apache.hadoop.util.Shell in 2.7 breaks <clinit> on Java 9 RC build;
> backport HADOOP-10775 to 2.7.x
> -------------------------------------------------------------------------------------------------------
>
> 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: Minor
> Labels: Java9
> Attachments: HADOOP-14586-branch-2.7-01.patch,
> HADOOP-14586-branch-2.7-02.patch
>
>
> 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:
> {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 not needed, {{compareTo}} also works without it,
> although it is still an invalid way to compare a version.
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