java - 使用 Java.util 的 Logger 和 FileHandler 类时，几秒钟后日志文件未更新

Question

我正在使用以下类“LoggerUtil”来记录到控制台和文件“logfile.log”。控制台的日志记录工作正常。但是，日志记录到“logfile.log”文件会在几条日志后停止。欢迎提出有关查找错误的任何建议。我附上下面的代码:

public class LoggerUtil {   
  public static final String LOGGERNAME = "project.logging";

  static {
      try {
          Logger.getLogger(LOGGERNAME).setUseParentHandlers(false);
          Handler ch = new ConsoleHandler();
          Handler fh = new FileHandler("logfile.log");
          SimpleFormatter sf = new SimpleFormatter();
          fh.setFormatter(sf);
          Logger.getLogger(LOGGERNAME).addHandler(ch);
          Logger.getLogger(LOGGERNAME).addHandler(fh);
          setHandlersLevel(Level.ALL);
      } catch (IOException | SecurityException ex) {
          Logger.getLogger(LoggerUtil.class.getName()).log(Level.SEVERE, null, ex);
      }
  }

  public static void setHandlersLevel(Level level) {
      Handler[] handlers = Logger.getLogger(LOGGERNAME).getHandlers();
      for (Handler h : handlers) {
          h.setLevel(level);
      }
      Logger.getLogger(LOGGERNAME).setLevel(level);
  }

  public static Logger getLogger() {
      return Logger.getLogger(LOGGERNAME);
  }
}

我在我项目的不同地方调用了下面的代码来记录:

LoggerUtil.getLogger().log(Level.INFO, "Message to be logged");

请注意，我的项目是多线程的。各种线程使用相同的文件进行日志记录。这可能是并发问题还是只是转移注意力!

Answer 1

硬引用您的记录器。经验法则是在您的类中使用静态最终字段。

public static final String LOGGERNAME = "project.logging";
//Pin logger in memory.
private static final Logger logger = Logger.getLogger(LOGGERNAME);

来自记录器。 getLogger(String)文档:

Note: The LogManager may only retain a weak reference to the newly created Logger. It is important to understand that a previously created Logger with the given name may be garbage collected at any time if there is no strong reference to the Logger.

当记录器被垃圾收集时，您的 ConsoleHandler 和 FileHandler 不会重新附加到新记录器。

使用 FindBugs，因为它检测到这个 bug pattern :

LG: Potential lost logger changes due to weak reference in OpenJDK (LG_LOST_LOGGER_DUE_TO_WEAK_REFERENCE)