MDC在异步环境中丢失：Amazon SWF日志上下文传播指南

import org.slf4j.MDC;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MdcAsyncPropagation {
    private static final Logger log = LoggerFactory.getLogger(MdcAsyncPropagation.class);

    /**
     * 包装一个Runnable，使其在新线程中恢复MDC上下文
     */
    public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
        return () -> {
            Map<String, String> oldContext = MDC.getCopyOfContextMap(); // 备份当前线程的MDC (如果存在)
            if (context != null) {
                MDC.setContextMap(context); // 恢复传入的MDC上下文
            }
            try {
                runnable.run();
            } finally {
                // 任务完成后，清理MDC，避免污染线程池中线程的MDC
                if (oldContext != null) {
                    MDC.setContextMap(oldContext); // 恢复旧的MDC上下文
                } else {
                    MDC.clear(); // 如果旧的MDC是空的，则清空
                }
            }
        };
    }

    /**
     * 包装一个Callable，使其在新线程中恢复MDC上下文
     */
    public static <V> Callable<V> wrap(final Callable<V> callable, final Map<String, String> context) {
        return () -> {
            Map<String, String> oldContext = MDC.getCopyOfContextMap();
            if (context != null) {
                MDC.setContextMap(context);
            }
            try {
                return callable.call();
            } finally {
                if (oldContext != null) {
                    MDC.setContextMap(oldContext);
                } else {
                    MDC.clear();
                }
            }
        };
    }

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executor = Executors.newFixedThreadPool(2);

        // 1. 在主线程设置MDC
        MDC.put("traceId", "main-request-123");
        MDC.put("userId", "userA");
        log.info("主线程日志，带有MDC信息。"); // 预期输出：traceId=main-request-123, userId=userA

        // 2. 捕获当前MDC上下文
        Map<String, String> mdcContextForAsync = MDC.getCopyOfContextMap();

        // 3. 提交一个异步任务，并传播MDC
        executor.submit(wrap(() -> {
            log.info("异步任务日志，MDC已传播。"); // 预期输出：traceId=main-request-123, userId=userA
            MDC.put("subTaskId", "task-001"); // 异步任务中可以添加自己的MDC
            log.info("异步任务日志，添加了新的MDC。"); // 预期输出：traceId=main-request-123, userId=userA, subTaskId=task-001
        }, mdcContextForAsync));

        // 4. 提交另一个异步任务，不传播MDC (对比用)
        executor.submit(() -> {
            log.info("未传播MDC的异步任务日志。"); // 预期输出：无traceId, 无userId
        });

        Thread.sleep(500); // 等待异步任务完成
        log.info("主线程日志，在异步任务之后。"); // 预期输出：traceId=main-request-123, userId=userA

        executor.shutdown();
        MDC.clear(); // 清理主线程的MDC
    }
}

{
  "timestamp": "2023-10-27T10:00:00.000Z",
  "level": "INFO",
  "message": "Starting workflow",
  "traceId": "workflow-12345",
  "activityInput": {
    "workflowId": "workflow-12345",
    "data": "..."
  }
}