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From "Uwe Schindler (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-3537) Add note about Java 7u1 and 6u29 to Lucene/Solr sites
Date Fri, 28 Oct 2011 08:08:32 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-3537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13138160#comment-13138160
] 

Uwe Schindler commented on LUCENE-3537:
---------------------------------------

There are several bugs, a complete report is here:
- [Main article|http://blog.thetaphi.de/2011/07/real-story-behind-java-7-ga-bugs.html]
- [Explanation of the string concat issues, this explains why StringConcat optimizations trigger
this|http://blog.thetaphi.de/2011/10/gotocon-aarhus-2011.html]
- [Discussion about the update release|http://blog.thetaphi.de/2011/10/java-7-update-1-released-does-it-fix.html]

In general: Use a recent JVM and don't use experimental tuning options. Otherwise you risk
data loss.

The Porter Stemmer SIGSEGV bug simply crashes the JVM and is caused by the String optimization.
The Data Corruption issues are triggered by loop optimizations and cannot be prevented in
Java 7 without u1 or significant performance loss (I emphasize: *significant*). In Java 6
with AggressiveOpts enabled, the index corruption can also occur but more seldom (it is not
easy to reproduce).
                
> Add note about Java 7u1 and 6u29 to Lucene/Solr sites
> -----------------------------------------------------
>
>                 Key: LUCENE-3537
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3537
>             Project: Lucene - Java
>          Issue Type: Task
>          Components: general/website
>            Reporter: Uwe Schindler
>
> Oracle confirmed, that the bugs leading to index corruption and SIGSEGV are fixed in
Java 7u1 and 6u29. We should post a message to the news sections revising the previous WARNING
(LUCENE-3349). I prepared something, please comment before i commit:
> {code:xml}
> <section><title>26 October 2011 - Java 7u1 fixes index corruption and crash
bugs in Apache Lucene Core and Apache Solr</title>
> <p>Oracle released <a href="http://www.oracle.com/technetwork/java/javase/7u1-relnotes-507962.html">Java
7u1</a> on October 19.
> According to the release notes and tests done by the Lucene committers, all bugs reported
on July 28 are fixed in this release,
> so code using Porter stemmer no longer crashes with <code>SIGSEGV</code>.
We were not able to experience any index corruption anymore,
> so it is safe to use Java 7u1 with Lucene Core and Solr.</p>
> <p>On the same day, Oracle released <a href="http://www.oracle.com/technetwork/java/javase/6u29-relnotes-507960.html">Java
6u29</a>
> fixing the same problems occurring with Java 6, if the JVM switches <code>-XX:+AggressiveOpts</code>
> or <code>-XX:+OptimizeStringConcat</code> were used. Of course, you should
<strong>not</strong> use experimental JVM options like
> <code>-XX:+AggressiveOpts</code> in production environments! We recommend
everybody to upgrade to this latest version 6u29.</p>
> <p>In case you upgrade to Java 7, remember that you may have to reindex, as the
unicode
> version shipped with Java 7 changed and tokenization behaves differently
> (e.g. lowercasing). For more information, read <code>JRE_VERSION_MIGRATION.txt</code>
> in your distribution package!</p>
> </section>
> {code}
> I plan to commit this later this afternoon.

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