使用Logger和FileHandler Class of Java.util时，几秒钟后日志文件没有更新 [英] Log File not being updated after few seconds while using Logger and FileHandler Class of Java.util

问题描述

我使用以下类'LoggerUtil'来记录到控制台和文件'logfile.log'。记录到控制台工作正常。但是，记录到'logfile.log'文件在几个日志后停止。任何有关查找错误的建议都会受到欢迎。我附上以下代码：

I am using the following Class 'LoggerUtil' for logging to console and to a file 'logfile.log'. The logging to console is working fine. However, logging to 'logfile.log' file stops after few logs. Any suggestions in locating the bug would be welcome. I am attaching the code below:

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);
  }
}

我从项目中的不同位置调用以下代码记录：

I call the following code from various places in my project to log:

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。这可能是一个并发问题，还是只是一个红鲱鱼！

Kindly note, my project is multithreaded. Various threads use the same file for logging. Could this be a concurrency issue or is that just a red herring!

推荐答案

对您的记录器进行硬性引用。经验法则是在类中使用静态最终字段。

Make a hard reference to your logger. Rule of thumb is to use a static final field in your class.

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

来自Logger。 getLogger（String）文档：

From the Logger.getLogger(String) documentation:

注意：LogManager可能只保留对新创建的Logger的弱引用。重要的是要理解，如果没有对Logger的强引用，则可以随时对先前创建的具有给定名称的Logger进行垃圾收集。

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不会重新连接到新的记录器。

When the logger is garbage collected your ConsoleHandler and FileHandler are not reattached to the new logger.

使用FindBugs因为它检测到这个错误模式：

Use FindBugs because it detects this bug pattern:

LG：由于OpenJDK中的弱引用导致记录器可能丢失（LG_LOST_LOGGER_DUE_TO_WEAK_REFERENCE）

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

这篇关于使用Logger和FileHandler Class of Java.util时，几秒钟后日志文件没有更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！