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
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Yueyu Lin
