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();
}
}
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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( "-" , "" );
}
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- 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" />
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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();
}
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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()));
}
}
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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();
}
};
}
}
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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;
}
}
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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);
}
}
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RestTemplate添加拦截器即可。
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restTemplate.setInterceptors(Arrays.asList(new RestTemplateTraceIdInterceptor()));
复制代码
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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();
}
}
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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
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转自:https://www.jb51.net/article/245347.htm
标签:13,traceId,MDC,boot,线程,Spring,TraceIdUtil,public From: https://www.cnblogs.com/tiancai/p/17622377.html