Jeff, Correct - there is no need to optimize the index after adding a document, and I would recommend against it especially when you move to 2.9 as you will not see any of the benefits of the changes to composite readers such as faster incremental warm-ups to filters and field caches.
I've never run Lucene.Net in the context of a web process and would actually recommend against that approach due to app pool recycling, opting for a service that exposed search functionality via WCF. What types of queries are you executing? Are you using filters or sorting? How often do you re-open the IndexReader that is used for searching? Re-opening the reader after each document addition can be an expensive process, especially if you are using filters and/or sorts. How are you refreshing the IndexReader? Regarding the IndexReader locking files, this is a feature which allows you to concurrently index and search on the same index and not have to worry about the IndexWriter deleting a segment file from underneath the searcher when a segment merge occurs. The first place to look would be to use a memory profiler to determine what is actually consuming the memory. I use the SciTech .NET Memory Profiler for such purposes. Michael -----Original Message----- From: Jeff Pennal [mailto:[email protected]] Sent: Tuesday, January 05, 2010 12:42 PM To: [email protected] Subject: Possible memory leak in Lucene.NET 2.4? Hello all, In doing some profiling of our Lucene code, I noticed that we were doing an optimize code after every update to our index. Though our index is relatively small (~75MB), the optimize task still look way to much time to run. I did some research and it seems like it would not be an issue to update our index without optimizing afterwords, the side effect being that we'd have more open file handles. I made that change and noticed some horrible performance side effects. The first thing I noticed was that the CPU for our web application (ASP.NET MVC) that read from the Index never went below 60-70% and was frequently pegged at 99%. In addition to the CPU spiking, the memory taken up by the w3wp.exe process quickly grew to around 800MB, which is about 300MB above normal. This has all the hallmarks of a memory leak somewhere. Finally, I noticed that the IndexReader was locking some of the files in the index folder even though the reader was set to nolock mode. This seemed to be cause of the increase in the number of files in the index folder. We have the IndexReader set to open once and then be shared among every request to the web application. My understanding is that this is the correct way to do this, and this never caused and issues when we were optimizing the index after every update. I know this is a pretty vague problem and there could be any number of issues involved here. However, if anyone could suggest areas to look into for possible solutions, it would be greatly appreciated. Thanks, Jeff
