大连中山网站建设,网站文章不收录怎么做,做淘宝客网站教程,网页设计的主要步骤一.MDC
1.MDC介绍
MDC#xff08;Mapped Diagnostic Context#xff0c;映射调试上下文#xff09;是 log4j 和 logback 提供的一种方便在多线程场景下记录日志的功能。MDC 可以看成是一个与当前线程绑定的Map#xff0c;可以往其中添加键值对。MDC 中包含的内容可以被同…一.MDC
1.MDC介绍
MDCMapped Diagnostic Context映射调试上下文是 log4j 和 logback 提供的一种方便在多线程场景下记录日志的功能。MDC 可以看成是一个与当前线程绑定的Map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。MDC 的内容则由程序在适当的时候保存进去。对于一个 Web 应用来说通常是在请求被处理的最开始保存这些数据。 简而言之MDC就是日志框架提供的一个InheritableThreadLocal所以它是线程安全的在项目代码中可以将键值对放入其中然后使用指定方式取出打印即可。 优点代码简洁日志风格统一不需要在log打印中手动拼写traceId即log.info(traceId:{} , traceId) 在 log4j 和 logback 的取值方式为 %X{traceid}2.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 getPropertyMap()返回当前线程的context map的直接引用不是拷贝副本 getCopyOfContextMap()返回当前线程的context map的一个副本对这个map的修改不会影响原来copyOnInheritThreadLocal中的内容。
二.MDC使用
1.使用方式
public class Constants {/*** 日志跟踪id名。*/public static final String TRACE_ID trace_id;/*** 请求头跟踪id名。*/public static final String HTTP_HEADER_TRACE_ID app_trace_id;
}
public class TraceIdUtil {public static String getTraceId(){return UUID.randomUUID().toString().replace(-,);}
}HTTP调用第三方服务接口全流程traceId需要第三方服务配合第三方服务需要添加拦截器拿到request header中的traceId并添加到MDC中
public class LogInterceptor implements HandlerInterceptor {Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {//如果有上层调用就用上层的IDString traceId request.getHeader(Constants.TRACE_ID);if (traceId null) {traceId TraceIdUtil.getTraceId();}MDC.put(Constants.TRACE_ID, traceId);return true;}Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)throws Exception {}Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)throws Exception {//调用结束后删除MDC.remove(Constants.TRACE_ID);}
}修改日志格式
property namepattern[TRACEID:%X{traceId}] %d{HH:mm:ss.SSS} %-5level %class{-1}.%M()/%L - %msg%xEx%n/property重点是%X{traceId}traceId和MDC中的键名称一致
2.存在问题
2.1.子线程日志打印丢失traceId
子线程在打印日志的过程中traceId将丢失当前线程创建的子线程获取不到ThreadLocal存储的键值 解决方式为重写线程池对于直接new创建线程的情况不考略【实际应用中应该避免这种用法】重写线程池无非是对任务进行一次封装
问题重现 GetMapping(getUserByName)public Result getUserByName(RequestParam String name){//主线程日志logger.info(getUserByName paramter name:name);for(int i0;i5;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线程traceId封装工具类
public class ThreadMdcUtil {public static void setTraceIdIfAbsent() {if (MDC.get(Constants.TRACE_ID) null) {MDC.put(Constants.TRACE_ID, TraceIdUtil.getTraceId());}}public static T CallableT wrap(final CallableT callable, final MapString, 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 MapString, String context) {return () - {if (context null) {MDC.clear();} else {MDC.setContextMap(context);}setTraceIdIfAbsent();try {runnable.run();} finally {MDC.clear();}};}
}说明【以封装Runnable为例】
判断当前线程对应MDC的Map是否存在存在则设置设置MDC中的traceId值不存在则新生成针对不是子线程的情况如果是子线程MDC中traceId不为null执行run方法重新返回的是包装后的Runnable在该任务执行之前【runnable.run()】先将主线程的Map设置到当前线程中【 即MDC.setContextMap(context)】这样子线程和主线程MDC对应的Map就是一样的了
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。
public class ThreadPoolExecutorMdcWrapper extends ThreadPoolExecutor {public ThreadPoolExecutorMdcWrapper(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,BlockingQueueRunnable workQueue) {super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);}public ThreadPoolExecutorMdcWrapper(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,BlockingQueueRunnable workQueue, ThreadFactory threadFactory) {super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);}public ThreadPoolExecutorMdcWrapper(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,BlockingQueueRunnable workQueue, RejectedExecutionHandler handler) {super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);}public ThreadPoolExecutorMdcWrapper(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,BlockingQueueRunnable workQueue, ThreadFactory threadFactory,RejectedExecutionHandler handler) {super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);}Overridepublic void execute(Runnable task) {super.execute(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));}Overridepublic T FutureT submit(Runnable task, T result) {return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()), result);}Overridepublic T FutureT submit(CallableT task) {return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));}Overridepublic Future? submit(Runnable task) {return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));}
}线程池配置
Configuration
public class ThreadPoolTaskExecutorConfig{//最大可用的CPU核数public static final int PROCESSORS Runtime.getRuntime().availableProcessors();Beanpublic 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:12.2.HTTP调用丢失traceId
在使用HTTP调用第三方服务接口时traceId将丢失需要对HTTP调用工具进行改造在发送时在request header中添加traceId在下层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所以只给出这几种HTTP调用的解决方式
1.HttpClient
实现HttpRequestInterceptor接口并重写process方法
如果调用线程中含有traceId则需要将获取到的traceId通过request中的header向下透传下去 public class HttpClientTraceIdInterceptor implements HttpRequestInterceptor {Overridepublic void process(HttpRequest httpRequest, HttpContext httpContext) throws HttpException, IOException {String traceId MDC.get(Constants.TRACE_ID);//当前线程调用中有traceId则将该traceId进行透传if (traceId ! null) {//添加请求体httpRequest.addHeader(Constants.TRACE_ID, traceId);}}
}为HttpClient添加拦截器
private static CloseableHttpClient httpClient HttpClientBuilder.create().addInterceptorFirst(new HttpClientTraceIdInterceptor()).build();2.OKHttp
– 实现Interceptor拦截器重写interceptor方法实现逻辑和HttpClient差不多如果能够获取到当前线程的traceId则向下透传
public class OkHttpTraceIdInterceptor implements Interceptor {Overridepublic Response intercept(Chain chain) throws IOException {String traceId MDC.get(Constants.TRACE_ID);Request request null;if (traceId ! null) {//添加请求体request chain.request().newBuilder().addHeader(Constants.TRACE_ID, traceId).build();}Response originResponse chain.proceed(request);return originResponse;}
}为OkHttp添加拦截器 private static OkHttpClient client new OkHttpClient.Builder().addNetworkInterceptor(new OkHttpTraceIdInterceptor()).build();3. RestTemplate
实现ClientHttpRequestInterceptor接口并重写intercept方法其余逻辑都是一样的不重复说明
public class RestTemplateTraceIdInterceptor implements ClientHttpRequestInterceptor {Overridepublic ClientHttpResponse intercept(HttpRequest httpRequest, byte[] bytes, ClientHttpRequestExecution clientHttpRequestExecution) throws IOException {String traceId MDC.get(Constants.TRACE_ID);if (traceId ! null) {httpRequest.getHeaders().add(Constants.TRACE_ID, traceId);}return clientHttpRequestExecution.execute(httpRequest, bytes);}
}为RestTemplate添加拦截器
restTemplate.setInterceptors(Arrays.asList(new RestTemplateTraceIdInterceptor()));2.3.第三方服务需要添加拦截器
需要第三方服务配合添加拦截器拿到request header中的traceId并添加到MDC中
public class LogInterceptor implements HandlerInterceptor {Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {//如果有上层调用就用上层的IDString traceId request.getHeader(Constants.TRACE_ID);if (traceId null) {traceId TraceIdUtil.getTraceId();}MDC.put(Constants.TRACE_ID, traceId);return true;}Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)throws Exception {}Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)throws Exception {//调用结束后删除MDC.remove(Constants.TRACE_ID);}
}先从request header中获取traceId从request header中获取不到traceId则说明不是第三方调用直接生成一个新的traceId将生成的traceId存入MDC中
