Yueyu Lin, >From what I can tell from a quick look at the method, that method need to >remain synchronized, so multiple threads don't accidentally re-read that >'indexTerms' (Term[] type). Even though the method is synchronized, it looks >like only the first invocation would enter that try/catch/finally block where >term reading happens. Subsequent calls to this method should exist quickly, >because indexTerms != null.
Are you sure this is causing the bottleneck for you? I believe the proper way to figure that out is to kill the JVM with a SIGnal that causes the JVM to dump thread information. That would tell you where the code is blocking. Also, if you have concrete suggestions for code changes, please post them to JIRA as diffs/patches. Otis ----- Original Message ---- From: yueyu lin <[EMAIL PROTECTED]> To: java-dev@lucene.apache.org Sent: Tuesday, May 9, 2006 3:53:55 AM Subject: Re: Multiple threads searching in Lucene and the synchronized issue. -- solution attached. Please trace the codes into the Lucene when searching. Here is a table about how invokations are called. The trace log: *Steps* *ClassName* *Functions* *Description* 1. org.apache.lucene.search.Searcher public final Hits search(Query query) It will call another search function. 2. org.apache.lucene.search.Searcher public Hits search(Query query, Filter filter) Only one line code. It will new a Hits. return new Hits(this, query, filter); 3. org.apache.lucene.search.Hits Hits(Searcher s, Query q, Filter f) Next, we will trace into the constructor to see what stuffs will be done. 4. org.apache.lucene.search.Hits Hits(Searcher s, Query q, Filter f) line 41 : weight = q.weight(s) This call will rewrite the Query if necessary, let us to see what will happen then. 5. org.apache.lucene.search.Query public Weight weight(Searcher searcher) line 92: Query query = searcher.rewrite(this); This call will begin to rewrite the Query. 6. *org.apache.lucene.search.IndexSearcher* public Query rewrite(Query original) NOTE: we only have one IndexSearcher which has one IndexReader. If there is any functioins that are synchronized, the query process will be queued. 7. org.apache.lucene.search.BooleanQuery public Query rewrite(IndexReader reader) line 396: Query query = c.getQuery().rewrite(reader); Here, BooleanQuery will get its subqueries and call their rewrite function. The function will require to pass a parameter: *IndexReader* that we only have one instance. >From the codes we will notice *TermQuery* will not be rewrote and * PrefixQuery* will be rewrote to several *TermQuery*s. So we ignore the * TermQuery* and look into the *PrefixQuery*. 8. org.apache.lucene.search.PrefixQuery public Query rewrite(IndexReader reader) line 41: TermEnum enumerator = reader.terms(prefix); Let's see what will happen then. 9. org.apache.lucene.index.SegmentReader public TermEnum terms(Term t) line 277: return tis.terms(t); SegmentReader is in fact an IndexReader's implementation. 10. org.apache.lucene.index.TermInfosReader public SegmentTermEnum terms(Term term) line 211:get(term); 11. org.apache.lucene.index.TermInfosReader TermInfo get(Term term) line 136:ensureIndexIsRead(); We finally find it! 12. org.apache.lucene.index.TermInfosReader private synchronized void ensureIndexIsRead() Let's analyze the function and to see why it's synchronized and how to improve it. On 5/9/06, Chris Hostetter <[EMAIL PROTECTED]> wrote: > > > : We found if we were using 2 IndexSearcher, we would get 10% > performance > : benefit. > : But if we increased the number of IndexSearcher from 2, the > performance > : improvement became slight even worse. > > Why use more then 2 IndexSearchers? > > Typically 1 is all you need, except for when you want to open and "warm > up" a new Searcher because you know your index has changed on disk and > you're ready for those changes to be visible. > > (I'm not arguing against your change -- concurrancy isn't my forte so i > have no opinion on wether your suggesting is good or not, i'm just > questioning the goal) > > Acctually .. i don't know a lot about the internals of IndexSearcher and > TermInfosReader, but according to your description of the problem... > > : The class org.apache.lucene.index.TermInfosReader , as you know, every > : IndexSearcher will have one TermInfosReader. Every query, one method in > the > : class must be called: > : private synchronized void ensureIndexIsRead() throws IOException . > Notice > > If the method isn't static, then how can two differnet instances of > IndexSearcher, each with their own TermInfosReader, block one another? > > > > > -Hoss > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- -- Yueyu Lin --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
