Never mind, folks. Just found an answer:
http://www.gossamer-threads.com/lists/lucene/java-user/110708
On Sun, May 22, 2016 at 10:20 AM, Jianbao (Jim) Tao <jianbao....@gmail.com>
wrote:
> Hi,
>
> I am new to lucene. I was following the example, IndexFiles, from the
> lucene demo package. However, one thing I find surpring is that the
> write.lock file is left over, even when the IndexWriter#close() method is
> called. Below are details.
>
> Environment:
> OS X Yosemite
> java version "1.8.0_72"
> Java(TM) SE Runtime Environment (build 1.8.0_72-b15)
> Java HotSpot(TM) 64-Bit Server VM (build 25.72-b15, mixed mode)
>
> lucene dependencies:
> <lucene.version>6.0.0</lucene.version>
> <dependency>
> <groupId>org.apache.lucene</groupId>
> <artifactId>lucene-core</artifactId>
> <version>${lucene.version}</version>
> </dependency>
> <dependency>
> <groupId>org.apache.lucene</groupId>
> <artifactId>lucene-analyzers-common</artifactId>
> <version>${lucene.version}</version>
> </dependency>
> <dependency>
> <groupId>org.apache.lucene</groupId>
> <artifactId>lucene-queryparser</artifactId>
> <version>${lucene.version}</version>
> </dependency>
>
> My Indexer and IndexerTest classes:
> ```
> @Slf4j
> public class Indexer implements AutoCloseable {
> private IndexWriter writer;
>
> public Indexer(String indexDir) throws IOException {
> Directory dir = FSDirectory.open(Paths.get(indexDir));
> Analyzer analyzer = new StandardAnalyzer();
> IndexWriterConfig iwc = new IndexWriterConfig(analyzer);
> iwc.setOpenMode(IndexWriterConfig.OpenMode.CREATE_OR_APPEND);
> writer = new IndexWriter(dir, iwc);
> }
>
> @Override
> public void close() throws IOException {
> writer.close();
> log.info("Indexer is successfully closed.");
> }
>
> public int index(String docDir) throws IOException {
> File[] files = new File(docDir).listFiles();
> for (File f : files) {
> if (f.isDirectory() || f.isHidden()) continue;
> indexFile(f.toPath());
> }
> return writer.numDocs();
> }
>
> private void indexFile(Path f) throws IOException {
> log.info("Indexing {}", f);
> try (InputStream stream = Files.newInputStream(f)){
> Document doc = new Document();
>
> doc.add(new StringField("path", f.toString(),
> Field.Store.YES));
> doc.add(new LongPoint("modified",
> Files.getLastModifiedTime(f).toMillis()));
> doc.add(new TextField("contents", new BufferedReader(new
> InputStreamReader(stream, StandardCharsets.UTF_8))));
> writer.updateDocument(new Term("path", f.toString()), doc);
> }
> }
> }
>
>
> @Slf4j
> public class IndexerTest {
> @Test
> public void testIndex() throws Exception {
> String indexDir = Shared.NOTES_INDEX_DIR; // Shared contains
> string constants.
> try (Indexer indexer = new Indexer(indexDir)) {
> int indexedDocs = indexer.index(Shared.NOTES_DIR);
> log.info("Indexed {} documents in {}", indexedDocs,
> Shared.NOTES_DIR);
> }
> }
> }
> ```
> After running the testIndex() method, I can see this log:
> 2016-05-22 09:50:17,532 INFO [main] Indexer - Indexer is successfully
> closed.
> This indicates that the IndexWriter is successfully closed. However, I am
> surprised to see that the write.lock still remains in the index directory.
> I did a little digging. It appears that the `NativeFSLockFactory` is used
> in my case. So, is it by design that the user is supposed to remove the
> write.lock file manually when NativeFSLockFactory is used? I'd expect this
> to be done automatically, but I guess there are probably important reasons
> behind this behavior. In any case, I am just curious to know why.
>
