thread.join(1000);

        assertEquals("All lines should be processed", 5000, receivedLines.size());
        assertEquals("First line", "Line number 0", receivedLines.get(0));
        assertEquals("Last line", "Line number 4999", receivedLines.get(4999));
    }

    @Test
    public void test_run_concurrentAccess() throws InterruptedException {
        String input = "concurrent1\nconcurrent2\nconcurrent3";

            // Verify content structure
            boolean hasThreadLine = lines.stream().anyMatch(line -> line.startsWith("Thread:"));
            boolean hasStackTraceLine = lines.stream().anyMatch(line -> line.startsWith("\tat "));

            assertTrue("Should contain thread information", hasThreadLine);
            assertTrue("Should contain stack trace information", hasStackTraceLine);

        String[] inputs = { "input" };
        CharMappingItem item = new CharMappingItem(1L, inputs, "output");

        // Test newline replacement in setNewOutput
        item.setNewOutput("line1\nline2\nline3");
        assertEquals("line1 line2 line3", item.getNewOutput());
    }

    @Test
    public void test_setNewOutput_withNull() {
        String[] inputs = { "input" };

     * Captures output from command execution with configurable line buffering.
     */
    protected static class InputStreamThread extends Thread {

        /** Buffered reader for input stream. */
        private BufferedReader br;

        /** List to store captured output lines. */
        private final List<String> list = new LinkedList<>();

        /** Maximum number of lines to buffer. */
        private final int maxLineBuffer;

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                // Remove comments
                final String replacedLine = line.replaceAll("#.*$", StringUtil.EMPTY).trim();

                // Skip empty lines or comment lines
                if (replacedLine.length() == 0) {
                    if (updater != null) {

            }
        }

        private String getPackageName(File file) throws IOException {
            try (Stream<String> lines = Files.lines(file.toPath())) {
                String packageLine = lines.filter(line -> line.startsWith("package"))
                    .findFirst()
                    .orElseThrow(() -> new IOException("Can't find package definition in file " + file));

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                // Remove comments
                final String replacedLine = line.replaceAll("#.*$", StringUtil.EMPTY).trim();

                // Skip empty lines or comment lines
                if (replacedLine.length() == 0) {
                    if (updater != null) {

        psOutput.forEach(line -> {
            Matcher commandLineArgsMatcher = commandLineArgsPattern.matcher(line);
            Matcher pidMatcher = pidPattern.matcher(line);
            if (commandLineArgsMatcher.find() && pidMatcher.find()) {
                String pid = pidMatcher.group(1);
                if (!MY_PID.equals(pid)) {
                    action.accept(pid, line);
                }
            }

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (line.length() == 0 || line.charAt(0) == '#') {
                    if (updater != null) {
                        updater.write(line);
                    }
                    continue; // ignore empty lines and comments
                }

                String[] inputs;

src/main/resources/
├── fess_label.properties           # Base English labels (fallback)
├── fess_label_[locale].properties  # Language-specific labels (~1,056 lines)
├── fess_message.properties         # Base English messages (fallback)
└── fess_message_[locale].properties # Language-specific messages (~200 lines)
```

### Naming Convention

- **Language only**: `fess_label_en.properties`, `fess_label_ja.properties`