Lucene's write lock is simple. There are four places that requires the write lock. Those are IndexReader.delete(int), IndexReader.setNorm(int,String,byte), IndexReader.undeleteAll(), and IndexWriter.<init>. Once you've used one of methods above, you should close that IndexReader or IndexWriter instance to release the write lock (and to avoid the Lock-obtain-timed-out exception).
For example, the following sequence should be okay. > IndexReader reader = IndexReader.open( DIR ); > reader.delete( new Term( "A", "B" ) ); > reader.close(); > IndexWriter writer = new IndexWriter( DIR, a, b ); > writer.add( oneDocument ); > writer.close(); But, a sequence following causes a "Lock obtain timed out" exception. > IndexReader reader = IndexReader.open( DIR ); > reader.delete( new Term( "A", "B" ) ); > IndexWriter writer = new IndexWriter( DIR, a, b ); Because, the write lock obtained at IndexReader.delete() wouldn't be removed by IndexReader.close() and "new IndexWriter()" sentence requires a write lock. On Fri, 21 Jan 2005 08:20:12 -0800 (PST), Otis Gospodnetic <[EMAIL PROTECTED]> wrote: > Hello Ashley, > > You can read/search while modifying the index, but you have to ensure > only one thread or only one process is modifying an index at any given > time. Both IndexReader and IndexWriter can be used to modify an index. > The former to delete Documents and the latter to add them. You have > to ensure these two operations don't overlap. > c.f. http://www.lucenebook.com/search?query=concurrent > > Otis > > > --- Ashley Steigerwalt <[EMAIL PROTECTED]> wrote: > > > I am a little fuzzy on the thread-safeness of Lucene, or maybe just > > java. > > From what I understand, and correct me if I'm wrong, Lucene takes > > care of > > concurrency issues and it is ok to run a query while writing to an > > index. > > > > My question is, does this still hold true if the reader and writer > > are being > > executed as separate programs? I have a cron job that will update > > the index > > periodically. I also have a search application on a web form. Is > > this going > > to cause trouble if someone runs a query while the indexer is > > updating? > > > > Ashley > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- Cheolgoo, Kang --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
