JVM crashes on Lucene DataInput.readVInt

Question

My JVM (1.6.0_29) keeps crashing on intensive use when indexing documents with Lucene. I get:

#
# A fatal error has been detected by the Java Runtime Environment         


        

Answer 1

these JDK issues are also fixed in 1.6.9_29 (not only 1.7.0u1). ReadVInt can no longer crash. So your crash is not related to any of the "famous java6/7 bugs" (the vint bug does not crash your JVM at all it just corrupts your index by returning wrong values - and this one is definitely fixed since Lucene 3.1).

But there is another chance you can crash your JVM: You are on a 64 bit platform (Linux), so the default directory implementation is MMapDirectory. Lucene uses a hack to be able to unmap mapped files from virtual address space. This is not allowed by the JVM itsself, but makes unmapping dependent on garbage collector, which is a problem for Lucene. By default MMapDirectory unmaps the files after closing the IndexInputs. MMapDirectory is not synchronized at all, so when another thread tries to access the IndexInput after unmapping it will access an unmapped address and will SIGSEGV.

If your code would be correct this cannot happen, but it looks like you are using an already closed IndexReader/IndexWriter to access the index. Before Lucene 3.5 (will come out soon), missing checks in IndexReader will make it possible that an already closed IndexReader with all its closed (and unmapped) IndexInputs tries to access index data and segfaults.

In 3.5 we added additional safety checks to prevent this illegal access, but its not 100% (as synchronization is missing). I would review the code and check that nothing accesses closed index.

A simple check to see if this is your issue would be to use NIOFSDirectory (slower on Linux) instead of MMapDirectory. If it does not crash and possibly throws AlreadyClosedExceptions, the bug is accessing closed indexes.

Answer 2

According to this article the following could cause it in Java 6 as well:

Please note: Also Java 6 users are affected, if they use one of those JVM options, which are not enabled by default: -XX:+OptimizeStringConcat or -XX:+AggressiveOpts

Are you using any of them?