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https://issues.apache.org/jira/browse/LUCENE-3349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13072452#comment-13072452
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Steven Rowe commented on LUCENE-3349:
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bq. In the case you upgrade to Java 7, remember that you have to reindex
everything, as the unicode version shipped with Java 7 changed and tokenization
behaves differently!
StandardTokenizer is not dependent on JVM Unicode version, so this statement is
neither true in the strict sense nor in the "average" sense, assuming the
"average" user employs StandardTokenizer/Analyzer.
> Place warning about today's released Java7 version on Lucene/Solr/Root
> webpage's news and send mail to java-user
> ----------------------------------------------------------------------------------------------------------------
>
> Key: LUCENE-3349
> URL: https://issues.apache.org/jira/browse/LUCENE-3349
> Project: Lucene - Java
> Issue Type: Sub-task
> Components: general/website
> Environment: Java7
> Reporter: Uwe Schindler
> Assignee: Uwe Schindler
>
> Today, JDK/JRE 1.7.0 GA was released by Oracle. Unfortunately they didn't fix
> the Hotspot problems affecting loops to be miscompiled (LUCENE-3335,
> LUCENE-3346). This can lead to Solr crashing with default configuration on
> startup or sudden index corrumption depending on configuration.
> We should send an email to the java-user and solr-user list describing the
> problem. Also place a note in the news section of Solr, Lucene Core and
> top-level website.
> I propose the following text:
> {quote}
> *Jul 28th, 2011: WARNING*
> Oracle released *Java 7* today. Unfortunately it contains some hotspot
> compiler optimizations, which miscompile some loops in Lucene's code (this
> affects all versions released until today, see Hotspot bug
> [http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7070134]). Solr users
> with the default configuration will have Java crashing with SIGSEGV as soon
> as they start to index documents, as one affected part is the well-known
> Porter stemmer (see LUCENE-3335). Other loops in Lucene may be miscompiled,
> too, leading to index corruption (especially on Lucene trunk with pulsing
> codec; other loops may be affected, too).
> These problems were detected only 5 days before the official Java 7 release,
> so Oracle had no time to fix those bugs, affecting also many more
> applications. In response to our questions, they proposed to include the
> fixes into service release u2 (eventually into service release u1, see
> [http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2011-July/005971.html]).
> This means you cannot use Lucene/Solr with Java 7 releases before Update 2!
> If you do, please don't open bug reports, it is not the committers' fault! At
> least disable loop optimizations using the -XX:-UseLoopPredicate JVM options
> to not risk index corruptions.
> Please note: Also Java 6 users are affected, if you use one of those JVM
> options, which are not enabled by default: -XX:+OptimizeStringConcat or
> -XX:+AggressiveOpts
> It is strongly recommended not to use any hotspot optimization switches in
> any Java version without extensive testing!
> In the case you upgrade to Java 7, remember that you have to reindex
> everything, as the unicode version shipped with Java 7 changed and
> tokenization behaves differently!
> {quote}
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