Hi everyone, A severe optimization bug in Java 7 is affecting the Apache Lucene project which is heavily used by Hibernate Search. If you are using any version of Hibernate Search and contemplate using Java 7, please read. In one line: do not use or you might get index corruption and VM crashes. Some details * a loop optimization bug is present in Java 7 * it can lead to either crash or index corruption when running Hibernate Search * Oracle is aware of the problem and is working for a fix for update 2 (and maybe update 1) * this bug also affect Java 6 VMs assuming you use some VM optimization options (-XX:+OptimizeStringConcat or -XX:+AggressiveOpts) A very nice and detailed explanation of the problem by Uwe from Lucene fame can be found at http://markmail.org/thread/kulrw4sm2nsshrta We are tracking the problem at https://hibernate.onjira.com/browse/HSEARCH-820 Emmanuel PS: many kudos to the Lucene community for being so open and reactive