Lucene IndexReader.reopen doesn't seem to work correctly

I have a problem with Lucene 2.4, the situation is as follows:

I have to deal with the possibility that there are two separate processes in the same Index directory and they must have the same data. This means that when one instance adds a document to the index, other instances of the application must find the added documents the next time they search. According to Lucene documentation IndexReader.reopen is what I need.

So, I came up with the following test test:

package de.samedi.searcher;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import java.io.IOException;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.FSDirectory;
import org.junit.Test;

public class LuceneReload {

    private IndexSearcher searcher1;
    private IndexSearcher searcher2;
    private FSDirectory directory1, directory2;
    private IndexWriter writer1, writer2;


    @Test
    public void testReload() throws Exception {
        String home = System.getProperty("user.home");
        this.directory1 = FSDirectory.getDirectory(home + "/testIndex");
        this.directory2 = FSDirectory.getDirectory(home + "/testIndex");
        this.writer1 = new IndexWriter(this.directory1, new StandardAnalyzer(), true, IndexWriter.MaxFieldLength.LIMITED);
        this.writer2 = new IndexWriter(this.directory2, new StandardAnalyzer(), true, IndexWriter.MaxFieldLength.LIMITED);

        // assert that we're empty
        assertFound(getSearcher1(), "test", 0);
        assertFound(getSearcher2(), "test", 0);

        add(this.writer1, "test");
        assertFound(getSearcher1(), "test", 1);
        assertFound(getSearcher2(), "test", 1);

        add(this.writer2, "foobar");
        assertFound(getSearcher1(), "foobar", 1);
        assertFound(getSearcher2(), "foobar", 1);
    }

    public void assertFound(IndexSearcher searcher, String q, int expected_number) {
        try {
            QueryParser parser = new QueryParser("name", new StandardAnalyzer());
            Query query = parser.parse(q);
            TopDocs t = searcher.search(query, null, 50);
            assertEquals(expected_number, t.totalHits);
        } catch (Exception e) {
            e.printStackTrace();
            fail();
        }

    }

    public IndexSearcher getSearcher1() throws CorruptIndexException, IOException {
        if (this.searcher1 == null) {
            this.searcher1 = new IndexSearcher(IndexReader.open(this.directory1));
        } else {
            IndexReader new_reader, old_reader;

            old_reader = this.searcher1.getIndexReader();
            new_reader = old_reader.reopen();

            if (new_reader != old_reader) {
                System.err.println("index1 changed");
                this.searcher1.close();
                old_reader.close();
                this.searcher1 = new IndexSearcher(new_reader);
            }
        }

        return this.searcher1;
    }

    public IndexSearcher getSearcher2() throws CorruptIndexException, IOException {
        if (this.searcher2 == null) {
            this.searcher2 = new IndexSearcher(this.directory2);
        } else {
            IndexReader new_reader, old_reader;

            old_reader = this.searcher2.getIndexReader();
            new_reader = old_reader.reopen();

            if (new_reader != old_reader) {
                System.err.println("index2 changed");
                this.searcher2.close();
                old_reader.close();
                this.searcher2 = new IndexSearcher(new_reader);
            }
        }

        return this.searcher2;
    }

    public void add(IndexWriter writer, String name) throws CorruptIndexException, IOException {
        Document d = new Document();
        d.add(new Field("name", name, Field.Store.YES, Field.Index.ANALYZED));
        writer.addDocument(d);
        writer.commit();
        IndexWriter.unlock(writer.getDirectory());
    }
}

      

When instead of calling reopen () instead of () are used

new_reader = IndexReader.open(this.directory1);

      

tests are in green.

I missed some important points

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1 answer


see IndexWriter # javadoc unlocking:

  /**
   * Forcibly unlocks the index in the named directory.
   * <P>
   * Caution: this should only be used by failure recovery code,
   * when it is known that no other process nor thread is in fact
   * currently accessing this index.
   */

      



I would not use this for normal operations.

Instead, open a new script and close it. This will work correctly, although it is best to use only one index index.

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