利用Spring?boot+LogBack+MDC實(shí)現(xiàn)鏈路追蹤

更新時(shí)間：2022年04月21日 09:45:14 作者：劍圣無(wú)痕?

這篇文章主要介紹了利用Spring?boot+LogBack+MDC實(shí)現(xiàn)鏈路追蹤，MDC?可以看成是一個(gè)與當(dāng)前線程綁定的哈希表，可以往其中添加鍵值對(duì)，下文詳細(xì)介紹需要的小伙伴可以參考一下

MDC介紹

MDC(Mapped Diagnostic Context，映射調(diào)試上下文)是 log4j 、logback及l(fā)og4j2 提供的一種方便在多線程條件下記錄日志的功能。MDC 可以看成是一個(gè)與當(dāng)前線程綁定的哈希表，可以往其中添加鍵值對(duì)。MDC 中包含的內(nèi)容可以被同一線程中執(zhí)行的代碼所訪問(wèn)。當(dāng)前線程的子線程會(huì)繼承其父線程中的 MDC 的內(nèi)容。當(dāng)需要記錄日志時(shí)，只需要從 MDC 中獲取所需的信息即可。

API說(shuō)明

clear() => 移除所有MDC
get (String key) => 獲取當(dāng)前線程MDC中指定key的值
getContext() => 獲取當(dāng)前線程MDC的MDC
put(String key, Object o) => 往當(dāng)前線程的MDC中存入指定的鍵值對(duì)
remove(String key) => 刪除當(dāng)前線程MDC中指定的鍵值對(duì) 。

MDC使用

1.攔截器

@Component
public class LogInterceptor implements HandlerInterceptor
{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //如果有上層調(diào)用就用上層的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 {
        //調(diào)用結(jié)束后刪除
        TraceIdUtil.remove();
    }
}

2.工具類

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

<property name="LOG_PATTERN" value="%date{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level [%X{requestId}] %logger{36} - %msg%n" />

重點(diǎn)是%X{requestId},requestId和MDC中的鍵名稱保持一致。

MDC 存在的問(wèn)題

至此基本的功能已經(jīng)實(shí)現(xiàn)，但是存在一下幾個(gè)問(wèn)題

多線程情況下，子線程中打印日志會(huì)丟失traceId.
HTTP跨服務(wù)之間的調(diào)用丟失traceId.

子線程日志打印丟失traceId

問(wèn)題重現(xiàn)：

  @LogAnnotation(model="用戶管理",func="查詢用戶信息",desc="根據(jù)用戶名稱")
    @GetMapping("getUserByName")
    public Result getUserByName(@RequestParam String name)
    {
        //主線程日志
        logger.info("getUserByName paramter name:"+name);
        for(int i=0;i<5;i++)
        {
           //子線程日志
            threadPoolTaskExecutor.execute(()->{
                logger.info("child thread:{}",name);
                userService.getUserByName(name); 
            });
        }
        return Result.success();
    }

運(yùn)行結(jié)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

從運(yùn)行的結(jié)果來(lái)看，子線程打印日志，日志中的traceId信息已經(jīng)丟失。

解決方案：

子線程在打印日志的過(guò)程中traceId將丟失，解決方案為重寫線程池(對(duì)于直接new Thread 創(chuàng)建線程的情況不考略),實(shí)際開(kāi)發(fā)中也需要禁止這種情況。

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?yàn)镾pring Boot ThreadPoolTaskExecutor 已經(jīng)對(duì)ThreadPoolExecutor進(jìn)行封裝，只需要繼承ThreadPoolTaskExecutor重寫相關(guān)的執(zhí)行方法即可。

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);
            }
            //設(shè)置traceId
            setTraceIdIfAbsent();
            try {
                runnable.run();
            } finally {
                MDC.clear();
            }
        };
    }
}

代碼說(shuō)明：

判斷當(dāng)前線程對(duì)應(yīng)MDC的Map是否存在，如果存在則設(shè)置
設(shè)置MDC中的traceId值，不存在則新生成，如果是子線程，MDC中traceId不為null
執(zhí)行run方法

線程池配置

@Configuration
public class ThreadPoolTaskExecutorConfig
{
    //最大可用的CPU核數(shù)
    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;
    }
}

重新運(yùn)行結(jié)果發(fā)現(xiàn)子線程能夠正常獲取traceid信息進(jìn)行跟蹤。

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調(diào)用丟失traceId

HTTP調(diào)用第三方服務(wù)接口時(shí)traceId丟失，需要在發(fā)送請(qǐng)求時(shí)在Request Header中添加traceId，在被調(diào)用方添加攔截器獲取header中的traceId添加到MDC中。

HTTP調(diào)用有多種方式，比較常見(jiàn)的有HttpClient、OKHttp、RestTemplate，以RestTemplate調(diào)用為例。

1.接口調(diào)用方

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添加攔截器即可。

restTemplate.setInterceptors(Arrays.asList(new RestTemplateTraceIdInterceptor()));
復(fù)制代碼

2.第三方服務(wù)需要添加攔截器

@Component
public class LogInterceptor implements HandlerInterceptor
{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //如果有上層調(diào)用就用上層的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 {
        //調(diào)用結(jié)束后刪除
        TraceIdUtil.remove();
    }
}

其他HttpClient、OKHttp的實(shí)現(xiàn)方式與RestTemplate基本相同，這里就不一一列舉。 Spring boot +logback+MDC實(shí)現(xiàn)全鏈路跟蹤內(nèi)容已經(jīng)講完了

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