FileNotFoundException: Corrupted Index?

[Olivier Jaquemet]

Hi all,

We are using the last version of lucene (1.9.1), and sometimes we end up 
with such error when opening one of the index our application uses:

java.io.FileNotFoundException: [...]/LuceneIndex/_ 46.fnm (No such file 
or directory)
      at java.io.RandomAccessFile.open(Native Method)
      at java.io.RandomAccessFile.<init>(RandomAccessFile.java:204)
      at 
org.apache.lucene.store.FSIndexInput$Descriptor.<init>(FSDirectory.java:425) 

      at org.apache.lucene.store.FSIndexInput.<init>(FSDirectory.java:434)
      at 
org.apache.lucene.store.FSDirectory.openInput(FSDirectory.java:324)
      at org.apache.lucene.index.FieldInfos.<init>(FieldInfos.java:56)
      at 
org.apache.lucene.index.SegmentReader.initialize(SegmentReader.java:144)
      at org.apache.lucene.index.SegmentReader.get(SegmentReader.java:129)
      at org.apache.lucene.index.SegmentReader.get(SegmentReader.java:110)
      at 
org.apache.lucene.index.IndexReader$1.doBody(IndexReader.java:154)
      at org.apache.lucene.store.Lock$With.run(Lock.java:109)
      at org.apache.lucene.index.IndexReader.open(IndexReader.java:143)
      at org.apache.lucene.index.IndexReader.open(IndexReader.java:138)

The only solution available in this case being to completely remove and 
recreate the index.
I have the "corrupted" index available for testing should you need it.

Apparently this corruption occurs if the JVM has crashed or was shutdown 
too violently (kill -9)
I was wondering how a corruption of a lucene index could occur and how 
to prevent it, fix it on reopening or in a last resort, detect it to be 
able to recreate the index.

Note that I already have that kind of hook in the code for shutdown:

   // clean writer reader and searcher correctly
   Thread shutdown = new Thread() {
     public void run() {
       if (reader != null) {
         try { reader.close(); }
         catch (IOException ex){ /*empty*/ }
         reader = null;
       }
       if (searcher != null) {
         try { searcher.close(); }
         catch (IOException ex){ /*empty*/ }
         searcher = null;
       }
     }
   };
   Runtime.getRuntime().addShutdownHook(shutdown);
  
Or, on opening, code such as:

     Directory indexDir = FSDirectory.getDirectory(luceneDir, 
!IndexReader.indexExists(luceneDir));
     IndexReader.unlock(indexDir); // unlock directory in case of 
unproper shutdown
     if (!IndexReader.indexExists(luceneDir)) {
       writer = new IndexWriter(indexDir, analyzer, true);
       writer.close();
     }

Any suggestion or remark?

Thanks!
--
Olivier Jaquemet <[EMAIL PROTECTED]>