Log4j和WatchService仅在打开日志文件后做出反应

Question

我使用Apache log4j记录器记录我的应用程序。这是记录器配置的重要部分：

<appender name="file" class="org.apache.log4j.RollingFileAppender">
    <param name="File" value="c:/data/logfile.txt" />        
    <param name="BufferedIO" value="false" />
    <param name="BufferSize" value="1" /> 
    <param name="Append" value="true" />
    <param name="MaxFileSize" value="30MB" />
    <param name="MaxBackupIndex" value="1" />
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d %-5p [%c] (%t) %m%n" />
    </layout>
</appender>

我观看文件更改的班级是这样的：

public static class FileWatcher {
    private Thread thread;
    private WatchService watchService;

    public void start(final Path file) throws IOException {
        watchService = FileSystems.getDefault().newWatchService();
        Path parent = file.getParent();
        parent.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE);
        System.out.println("Going to watch " + file);

        thread = new Thread(() -> {
            while (true) {
                WatchKey wk = null;
                try {
                    wk = watchService.take();
                    for (WatchEvent<?> event : wk.pollEvents()) {
                        Path changed = parent.resolve((Path) event.context());
                        if (Files.exists(changed) && Files.isSameFile(changed, file)) {
                            System.out.println("File change event: " + changed);
                            break;
                        }
                    }
               } catch (InterruptedException e) {
                    System.out.println("Ending my watch");
                    Thread.currentThread().interrupt();
                    break;
                } catch (Exception e) {
                    System.out.println("Error while reloading cert");
                } finally {
                    if (wk != null) {
                        wk.reset();
                    }
                }
            }
        });
        thread.start();
    }

    public void stop() {
        thread.interrupt();
        try {
            watchService.close();
        } catch (IOException e) {
            System.out.println("Error closing watch service");
        }
    }
}

实例化是这样的

FileWatcher watcher = new FileWatcher();
    try {
        watcher.start(file);
    } catch (IOException e1) {
        // TODO Auto-generated catch block
    }

通常一切都按预期工作，但是唯一的事情是，当我使用外部编辑器或通过以下方式打开（已更改）文件时，WatchService仅对更改后的文件做出反应：

File f = new File(path);
StringBuilder builder = readFile(f);

该应用程序当前在Windows 10上运行。 那么，为什么WatchService不能对文件更改立即做出反应？