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