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From "Mark Modrall" <MModr...@glgroup.com>
Subject More frustration with Lucene/Java file i/o on Windows
Date Fri, 18 Aug 2006 14:33:31 GMT
Hi...

 

            It was a little comforting to know that other people have
seen Windows Explorer refreshes crash java Lucene on Windows.  We seem
to be running into a long list of file system issues with Lucene, and I
was wondering if other people had noticed these sort of things (and
hopefully any tips and tricks for working around them).

 

            We've got a process running as a Windows service that's
trying to keep a set of Lucene indexes up-to-date from a database.  The
corpus is pretty small, so we copy the last index build to a temp
directory and then try to do an incremental index of the changes on the
working copy.  Since our software is evolving, we've put a version
number in the meta data of the index files which we check when we're
starting up.  If the version numbers don't match, we scrap the whole
thing and start over.  The problem is that java Lucene on Windows
doesn't do "scrap" very well.

 

            The current hypothesis is that File.renameTo, File.delete,
and other jvm operations on windows fail if there is any other handle
open on the file and that Lucene objects aren't closing/finalizing their
file handles cleanly/reliably so other things blow up later.

 

            Here's the chain of events we had in our service process
last night:

20060817T165611.682,EDT [Indexer.java 813]: Exception occurred deleting
document 183971: Lock obtain timed out:
Lock@C:\WINDOWS\TEMP\lucene-22b8462f0f541160a41abfdff8d52f94-write.lock

20060817T165612.682,EDT [Indexer.java 813]: Exception occurred deleting
document 257265: Lock obtain timed out:
Lock@C:\WINDOWS\TEMP\lucene-22b8462f0f541160a41abfdff8d52f94-write.lock

20060817T165613.744,EDT [Indexer.java 1184]: Indexing failure, db
changes will be rolled back and partial index deleted.

java.io.IOException: Lock obtain timed out:
Lock@C:\WINDOWS\TEMP\lucene-22b8462f0f541160a41abfdff8d52f94-write.lock

            at org.apache.lucene.store.Lock.obtain(Lock.java:56)

            at
org.apache.lucene.index.IndexReader.aquireWriteLock(IndexReader.java:489
)

            at
org.apache.lucene.index.IndexReader.deleteDocument(IndexReader.java:514)

            at
org.apache.lucene.index.IndexReader.deleteDocuments(IndexReader.java:541
)

            at ...Indexer.buildIncrementalIndex(Indexer.java:915)

...

 

Why it couldn't get that temporary lock file, I don't know.  The same
process runs continuously, and I don't know if Lucene reuses the same
tmpnames from run to run.  If the files were left around because of
these JVM File system errors, maybe that would explain it.

 

The "partial index deleted" part of our message means that we did a
recursive (java) delete of all the index directories we were working
with.  Our attempt to clean the slate got everything but
contact_index\_3zhe.cfs.

 

An hour later, we come back and try to start another index build.  We
find the directory still exists, so we try to validate the index version
number using

            searcher = new
IndexSearcher(FSDirectory.getDirectory(indexFile, false));

            TermQuery tq = new TermQuery(new
Term(METADATA_DOCUMENT_FIELD, METADATA_DOCUMENT_FIELD_VALUE));

            Hits h = searcher.search(tq);

            if (h.length() == 1)

            ...

        finally

        {

            if (searcher != null)

            {

                try { searcher.close(); } catch (Exception e) { /*
ignore */ }

            }

        }

 

Obviously with only the _3zhe.cfs file left, it's not a valid index, so
the attempt to get the metadata fails.  No matter what happens, we do a
searcher.close().  My suspicion is that IndexSearch.close() isn't really
doing a File.close() on all the files it's using, so you have to wait
until searcher is garbage collected and its file objects finalized
before things will work - because immediately after this check, Lucene
fails a full build with

20060817T175614.323,EDT [Indexer.java 843]: Error building full index

java.io.IOException: Cannot delete
\\xx.xx.xx.xx\indexbuild2\contact_index\_3zhe.cfs

            at
org.apache.lucene.store.FSDirectory.create(FSDirectory.java:198)

            at
org.apache.lucene.store.FSDirectory.getDirectory(FSDirectory.java:144)

            at
org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:224)

...

 

Doing a full build, Lucene does it's own attempt to clear out the
leftovers which fails because it can't delete the file.  And we're stuck
in this loop all night.

 

The guy who wrote the Indexing code says the version check is the only
place in the code where we have an IndexSearcher created using a file
path string - that all others have a pre-existing IndexReader.  He wants
me to try it that way instead, so that we can explicitly close the
reader and hopefully clear that loose file handle.

 

Sorry for the long-winded vent, but does anyone have any advice for
getting java lucene working on windows?  Any idea why it would seize up
on the lock files?  This service process is the only lucene process on
the system, and the finished indexes are copied off to another server to
serve the search requests, so it's puzzling that the daemon process
would block itself...  Anyone know if an IndexReader.close() would do a
better job of cleaning up the file handles than IndexSearcher.close()?

 

Thanks

-Mark

 
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