I won't SWEAR to it, but I think that in my coding experiments, when I called the constructor of a searcher, which takes a path to the index, while an IndexModifier had the index open, the line failed.
--- Digy <[EMAIL PROTECTED]> wrote: > Many Searchers & one Indexer can work concurrently. What I want to try to > say is you can not open two IndexWriter for the same Index. > > DIGY. > > -----Original Message----- > From: Corey Trager [mailto:[EMAIL PROTECTED] > Sent: Sunday, October 12, 2008 5:00 AM > To: lucene-net-user@incubator.apache.org > Subject: RE: Multiple threads updating/reading the same index in an ASP.NET > website. - IndexModifier > > Digg - thanks. I originally wrote this at StackOverflow.com. Do you think I > understand things > now, based on what I wrote here: > > > "....After reading docs and experimentation, this is what I think I've > learned: There are two > issues, thread safety and concurrency. Multithreading is "safe" in that you > can't do anything bad > to the index. But, it's safe at the cost of just one object having a lock on > the index at one > time. The second object will come along and throw an exception. So, you > can't leave a search open > and expect a writer in another thread to be able to update the index. And if > a thread is busy > updating the index, then trying to create a searcher will fail. > > Also, Searchers see the index as it was at the time that they open it, so if > you keep them around, > and update the index, they won't see the updates. > > I wanted my searchers to see the latest updates. > > My design, and it seems to be working so far, is that my writers and > searchers share a lock, so > that they don't fail - they just wait - until the current write or search is > done...." > > > --- Digy <[EMAIL PROTECTED]> wrote: > > > Sorry, I forgot to say that I was talking about Lucene.Net 2.3.1 > > In Version 2.3.1, IndexWriter class has UpdateDocuments and > DeleteDocuments > > methods. So you don't have to use > > IndexModifier to add or delete documents. > > > > (IndexModifier is a wrapper for IndexWriter+IndexReader. If you call > > AddDocument it closes IndexReader(if open), opens the IndexWriter and > calls > > its AddDocument method. If you want to delete a document it closes the > > IndexWriter(if open), opens the IndexReader and then calls its > > DeleteDocuments method. So it is not an efficient implementation. > Therefore > > I don't think that having one instance of IndexModifier will change things > > much) > > > > >In the sample code, and my code, I see that there's a call to "Close" on > > IndexSearcher. Should I > > >omit that call, and leave it always open? > > > > Again for 2.3.1, IndexSearcher will not "see" the updates made by > > IndexWriter unless you reopen it. > > > > DIGY > > > > > > -----Original Message----- > > From: Corey Trager [mailto:[EMAIL PROTECTED] > > Sent: Sunday, October 12, 2008 12:52 AM > > To: lucene-net-user@incubator.apache.org > > Subject: RE: Multiple threads updating/reading the same index in an > ASP.NET > > website. - IndexModifier > > > > And, the same with IndexModifier, right? I should have one single > instance > > of it and all threads > > use that same instance? > > > > --- Digy <[EMAIL PROTECTED]> wrote: > > > > > Yes Lucene has build-in concurrency management. You can freely search > and > > > update the same index in different threads. One point here is that you > > have > > > to use the same instance of the IndexWriter in updating threads. Trying > to > > > open the same index twice will throw exception. It is also recommended > to > > > share a single IndexSearcher across threads for better performance. > > > > > > DIGY > > > > > > -----Original Message----- > > > From: Corey Trager [mailto:[EMAIL PROTECTED] > > > Sent: Saturday, October 11, 2008 7:36 PM > > > To: lucene-net-user@incubator.apache.org > > > Subject: Multiple threads updating/reading the same index in an ASP.NET > > > website. > > > > > > Does Lucene.Net have built into it logic for managing concurrency, > > multiple > > > threads? If a > > > request comes to my website that triggers a thread to update the index, > > and > > > another request comes > > > on another thread that also triggers a request to update, or even read, > > the > > > index, does Lucene > > > handle the management of concurrency, or do I need to? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
