Hi Paul, If I understand your setup correctly, it looks like you are running multiple threads that create IndexWriter for the ame directory. That's a "no no".
This section (first hit) describes all various concurrency issues with regards to adds, updates, optimization, and searches: http://www.lucenebook.com/search?query=concurrent IndexSearcher (IndexReader, really) does take a snapshot of the index state when it is opened, so at that time the index segments listed in segments should be in a complete state. It also reads index files when searching, of course. Otis --- Paul Mellor <[EMAIL PROTECTED]> wrote: > Hi, > > I've read from various sources on the Internet that it is perfectly > safe to > simultaneously search a Lucene index that is being updated from > another > Thread, as long as all write access to the index is synchronized. > But does > this apply only to updating the index (i.e. deleting and adding > documents), > or to a complete re-indexing (i.e. create a new IndexWriter with the > 'create' argument true and then re-add all the documents)? > > I have a class which encapsulates all access to my index, so that > writes can > be synchronized. This class also exposes a method to obtain an > IndexSearcher for the index. I'm running unit tests to test this > which > create many threads - each thread does a complete re-indexing and > then > obtains an IndexSearcher and does a query. > > I'm finding that with sufficiently high numbers of threads, I'm > getting the > occasional failure, with the following exception thrown when > attempting to > construct a new IndexWriter (during the reindexing) - > > java.io.IOException: couldn't delete _a.f1 > at org.apache.lucene.store.FSDirectory.create(FSDirectory.java:166) > at > org.apache.lucene.store.FSDirectory.getDirectory(FSDirectory.java:135) > at > org.apache.lucene.store.FSDirectory.getDirectory(FSDirectory.java:113) > at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:151) > ... > > The exception occurs quite infrequently (usually for somewhere > between 1-5% > of the Threads). > > Does the IndexSearcher take a 'snapshot' of the index at creation? > Or does > it access the filesystem whilst searching? I am also synchronizing > creation > of the IndexSearcher with the write lock, so that the IndexSearcher > is not > created whilst the index is being recreated (and vice versa). But do > I need > to ensure that the IndexSearcher cannot search whilst the index is > being > recreated as well? > > Note that a similar unit test where the threads update the index > (rather > than recreate it from scratch) works fine, as expected. > > This is running on Windows 2000. > > Any help would be much appreciated! > > Paul > > This e-mail and any files transmitted with it are confidential and > intended > solely for the use of the individual or entity to whom they are > addressed. > If you are not the intended recipient, you should not copy, > retransmit or > use the e-mail and/or files transmitted with it and should not > disclose > their contents. In such a case, please notify > [EMAIL PROTECTED] > and delete the message from your own system. Any opinions expressed > in this > e-mail and/or files transmitted with it that do not relate to the > official > business of this company are those solely of the author and should > not be > interpreted as being endorsed by this company. > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
