多线程情形下，日志链路traceId、spanId的传递

创建线程池异步调用服务的情形中，子线程在打印日志的过程中traceId将丢失

解决思路：重写线程池，对任务进行一次封装，在调度任务的之前将链路塞入MDC。几乎所有的情形下很少会new线程池(及其不推荐使用)，自带的创建线程池的方案也不推荐使用，阿里巴巴开发手册推荐创建线程池的方案是使用ThreadPoolExecutor创建线程池，线程池创建大小，自定义名称，自定义拒绝策略等优点在此不多赘述

直接上代码：

import com.csrcb.constants.MyConstant;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.MDC;

import java.util.Map;
import java.util.UUID;
import java.util.concurrent.Callable;

/**
 * @Classname ThreadPoolMDCFilter
 * @Description 多线程MDC塞入
 * @Date 2021/8/20 17:44
 * @Created by gangye
 */
public class ThreadPoolMDCFilter {

    public static void setSleuthTraceId(){
        if (StringUtils.isNotBlank(MDC.get(MyConstant.TRACE_ID_MDC_FIELD))){
            MDC.put(MyConstant.TRACE_ID_HTTP_FIELD, MDC.get(MyConstant.TRACE_ID_MDC_FIELD));//设置X-B3-TraceId
        }
        if (StringUtils.isNotBlank(MDC.get(MyConstant.SPAN_ID_MDC_FIELD))){
            MDC.put(MyConstant.PARENT_SPAN_ID_HTTP_FIELD,MDC.get(MyConstant.SPAN_ID_MDC_FIELD));
            MDC.put(MyConstant.PARENT_SPAN_ID_MDC_FIELD,MDC.get(MyConstant.SPAN_ID_MDC_FIELD));
        }
        String spanIdNew = UUID.randomUUID().toString().replace("-","").substring(0,16);
        MDC.put(MyConstant.SPAN_ID_HTTP_FIELD, spanIdNew);//设置X-B3-SpanId供外部使用
        MDC.put(MyConstant.SPAN_ID_MDC_FIELD, spanIdNew);//设置X-B3-SpanId供外部使用
    }

    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);
            }
            setSleuthTraceId();
            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);
            }
            setSleuthTraceId();
            try {
                runnable.run();
            } finally {
                MDC.clear();
            }
        };
    }

}

import org.slf4j.MDC;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.*;

/**
 * @Classname ThreadPoolExecutorMdcUtil
 * @Description 将MDC写入多线程的线程池工具，实例化的时候需要无参构造然后set
 * @Date 2021/8/20 17:50
 * @Created by gangye
 */
public class ThreadPoolExecutorMdcUtil extends ThreadPoolTaskExecutor {

    //重写执行方法，将MDC塞入
    @Override
    public void execute(Runnable task) {
        super.execute(ThreadPoolMDCFilter.wrap(task, MDC.getCopyOfContextMap()));
    }

    @Override
    public <T> Future<T> submit(Callable<T> task) {
        return super.submit(ThreadPoolMDCFilter.wrap(task, MDC.getCopyOfContextMap()));
    }

    @Override
    public Future<?> submit(Runnable task) {
        return super.submit(ThreadPoolMDCFilter.wrap(task, MDC.getCopyOfContextMap()));
    }
}

创建线程池的时候注意使用我们自定义的线程是的类