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.
