Does each thread have its own IndexWriter? This could cause the issue you describe.
IndexWriter is thread-safe so that multiple threads can use the same instance, however you will see a performance degradation compared to only having one thread modify the index. We've done quite a bit of testing for that case a while back and only have one thread modifying an index at a time. Michael -----Original Message----- From: Li Bing [mailto:[email protected]] Sent: Wednesday, October 28, 2009 10:57 PM To: [email protected] Cc: Li Bing - Gmail Subject: Exceptions When Indexing with Multi-threading Dear all, Today I got exceptions when indexing with multi-threading. It says that "deletable.new" or "segments.new" are accessed by other processes. So it cannot rename ... However, I have used "ReaderWriterSlim" lock to avoid the relevant folders to be accessed by multiple threads at the same time. For example, if the indexing is done in D:\Test,円 I use "ReaderWriterSlim" to prevent other threads from writing in the folder. I think the above exceptions should not happen if I do that. However, it is NOT true. Why? Any other ways to avoid the problem? Thanks so much! LB