利用Spring boot+LogBack+MDC实现链路追踪

这篇文章主要介绍了利用Spring boot+LogBack+MDC实现链路追踪，MDC 可以看成是一个与当前线程绑定的哈希表，可以往其中添加键值对，下文详细介绍需要的小伙伴可以参考一下
 
 

MDC介绍

MDC(Mapped Diagnostic Context，映射调试上下文)是 log4j 、logback及log4j2 提供的一种方便在多线程条件下记录日志的功能。MDC 可以看成是一个与当前线程绑定的哈希表，可以往其中添加键值对。MDC 中包含的内容可以被同一线程中执行的代码所访问。当前线程的子线程会继承其父线程中的 MDC 的内容。当需要记录日志时，只需要从 MDC 中获取所需的信息即可。

API说明

  • clear() => 移除所有MDC
  • get (String key) => 获取当前线程MDC中指定key的值
  • getContext() => 获取当前线程MDC的MDC
  • put(String key, Object o) => 往当前线程的MDC中存入指定的键值对
  • remove(String key) => 删除当前线程MDC中指定的键值对 。

MDC使用

1.拦截器

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@Component
public class LogInterceptor implements HandlerInterceptor
{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //如果有上层调用就用上层的ID
        String traceId = request.getHeader(TraceIdUtil.TRACE_ID);
        if (StringUtil.isEmpty(traceId))
        {
            TraceIdUtil.setTraceId(TraceIdUtil.generateTraceId());
        }
        else
        {
            TraceIdUtil.setTraceId(traceId);
        }
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
            throws Exception
    {
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        //调用结束后删除
        TraceIdUtil.remove();
    }
}

2.工具类

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public class TraceIdUtil
{
  public static final String TRACE_ID = "requestId";
  public static String getTraceId()
  {
     String traceId =(String) MDC.get(TRACE_ID);
     return traceId == null ? "" : traceId;
  }
  public static void setTraceId(String traceId)
  {
      MDC.put(TRACE_ID,traceId);
  }
  public static void remove()
  {
      MDC.remove(TRACE_ID);
  }
  public static void clear()
  {
      MDC.clear();
  }
  public static String generateTraceId() {
     return UUID.randomUUID().toString().replace("-", "");
  }
  • 日志文件配置
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<property name="LOG_PATTERN" value="%date{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level [%X{requestId}] %logger{36} - %msg%n" />

重点是%X{requestId},requestId和MDC中的键名称保持一致。

MDC 存在的问题

至此基本的功能已经实现，但是存在一下几个问题

  • 多线程情况下，子线程中打印日志会丢失traceId.
  • HTTP跨服务之间的调用丢失traceId.

子线程日志打印丢失traceId

问题重现：

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@LogAnnotation(model="用户管理",func="查询用户信息",desc="根据用户名称")
  @GetMapping("getUserByName")
  public Result getUserByName(@RequestParam String name)
  {
      //主线程日志
      logger.info("getUserByName paramter name:"+name);
      for(int i=0;i<5;i++)
      {
         //子线程日志
          threadPoolTaskExecutor.execute(()->{
              logger.info("child thread:{}",name);
              userService.getUserByName(name);
          });
      }
      return Result.success();
  }

运行结果：

2022-03-13 12:45:44.156 [http-nio-8089-exec-1] INFO  [ec05a600ed1a4556934a3afa4883766a] c.s.fw.controller.UserController - getUserByName paramter name:1
2022-03-13 12:45:44.173 [Pool-A1] INFO  [] c.s.fw.controller.UserController - child thread:1

从运行的结果来看，子线程打印日志，日志中的traceId信息已经丢失。

解决方案：

子线程在打印日志的过程中traceId将丢失，解决方案为重写线程池(对于直接new Thread 创建线程的情况不考略),实际开发中也需要禁止这种情况。

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public class ThreadPoolExecutorMdcWrapper extends ThreadPoolTaskExecutor
{
    private static final long serialVersionUID = 3940722618853093830L;
    @Override
    public void execute(Runnable task)
    {
        super.execute(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
    @Override
    public <T> Future<T> submit(Callable<T> task)
    {
        return super
                .submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
    @Override
    public Future<?> submit(Runnable task)
    {
        return super
                .submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
}

因为Spring Boot ThreadPoolTaskExecutor 已经对ThreadPoolExecutor进行封装，只需要继承ThreadPoolTaskExecutor重写相关的执行方法即可。

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public class ThreadMdcUtil
{
    public static void setTraceIdIfAbsent() {
        if (MDC.get(TraceIdUtil.TRACE_ID) == null)
        {
            MDC.put(TraceIdUtil.TRACE_ID, TraceIdUtil.generateTraceId());
        }
    }
    public static <T> Callable<T> wrap(final Callable<T> callable, final Map<String, String> context) {
        return () -> {
            if (context == null) {
                MDC.clear();
            } else {
                MDC.setContextMap(context);
            }
            setTraceIdIfAbsent();
            try {
                return callable.call();
            } finally {
                MDC.clear();
            }
        };
    }
    public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
        return () -> {
            if (context == null) {
                MDC.clear();
            } else {
                MDC.setContextMap(context);
            }
            //设置traceId
            setTraceIdIfAbsent();
            try {
                runnable.run();
            } finally {
                MDC.clear();
            }
        };
    }
}

代码说明：

  • 判断当前线程对应MDC的Map是否存在，如果存在则设置
  • 设置MDC中的traceId值，不存在则新生成，如果是子线程，MDC中traceId不为null
  • 执行run方法

线程池配置

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@Configuration
public class ThreadPoolTaskExecutorConfig
{
    //最大可用的CPU核数
    public static final int PROCESSORS = Runtime.getRuntime().availableProcessors();
    @Bean
    public ThreadPoolExecutorMdcWrapper getExecutor()
    {
        ThreadPoolExecutorMdcWrapper executor =new ThreadPoolExecutorMdcWrapper();
        executor.setCorePoolSize(PROCESSORS *2);
        executor.setMaxPoolSize(PROCESSORS * 4);
        executor.setQueueCapacity(50);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("Task-A");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
        executor.initialize();
        return executor;
    }
}

重新运行结果发现子线程能够正常获取traceid信息进行跟踪。

2022-03-13 13:19:30.688 [Task-A1] INFO  [482929425cbc4476a4e7168615af7890] c.s.fw.controller.UserController - child thread:1
2022-03-13 13:19:31.003 [Task-A1] INFO  [482929425cbc4476a4e7168615af7890] c.s.fw.service.impl.UserServiceImpl - name:1

HTTP调用丢失traceId

HTTP调用第三方服务接口时traceId丢失，需要在发送请求时在Request Header中添加traceId，在被调用方添加拦截器获取header中的traceId添加到MDC中。

HTTP调用有多种方式，比较常见的有HttpClient、OKHttp、RestTemplate，以RestTemplate调用为例。

1.接口调用方

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public class RestTemplateTraceIdInterceptor implements
        ClientHttpRequestInterceptor
{
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body,
            ClientHttpRequestExecution clientHttpRequestExecution) throws IOException
    {
        String traceId=MDC.get("requestId");
        if(traceId!=null)
        {
            request.getHeaders().set("requestId", traceId);
        }
        else
        {
            request.getHeaders().set("requestId", UUID.randomUUID().toString().replace("-", ""));
        }
        return clientHttpRequestExecution.execute(request, body);
    }
}

RestTemplate添加拦截器即可。

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restTemplate.setInterceptors(Arrays.asList(new RestTemplateTraceIdInterceptor()));
复制代码

2.第三方服务需要添加拦截器

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@Component
public class LogInterceptor implements HandlerInterceptor
{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //如果有上层调用就用上层的ID
        String traceId = request.getHeader(TraceIdUtil.TRACE_ID);
        if (StringUtil.isEmpty(traceId))
        {
            TraceIdUtil.setTraceId(TraceIdUtil.generateTraceId());
        }
        else
        {
            TraceIdUtil.setTraceId(traceId);
        }
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
            throws Exception
    {
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        //调用结束后删除
        TraceIdUtil.remove();
    }
}

其他HttpClient、OKHttp的实现方式与RestTemplate基本相同，这里就不一一列举。 Spring boot +logback+MDC实现全链路跟踪内容已经讲完了

到此这篇关于利用Spring boot+LogBack+MDC实现链路追踪的文章就介绍到这了,更多相关Spring boot 链路追踪内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

 

转自：https://www.jb51.net/article/245347.htm

posted @ 2023-08-11 10:23  甜菜波波  阅读(1445)  评论(0)  编辑  收藏  举报