异步线程获取上下文的MDC信息

异步线程traceId如何传递_new thread子线程传递traceid-CSDN博客

 

1. 重写线程池,来实现自定义线程池

a.下面的工具类，分别在Callable和Runnable异步任务执行前通过MDC.setContextMap(context)设置请求映射上下文

import org.slf4j.MDC;
import org.springframework.util.CollectionUtils;
 
import java.util.Map;
import java.util.concurrent.Callable;
 
/**
 * @desc: 定义MDC工具类，支持Runnable和Callable两种，目的就是为了把父线程的traceId设置给子线程
 */
public class MdcUtil {
 
    public static <T> Callable<T> wrap(final Callable<T> callable, final Map<String, String> context) {
        return () -> {
            if (CollectionUtils.isEmpty(context)) {
                MDC.clear();
            } else {
                MDC.setContextMap(context);
            }
            try {
                return callable.call();
            } finally {
                // 清除子线程的，避免内存溢出，就和ThreadLocal.remove()一个原因
                MDC.clear();
            }
        };
    }
 
    public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
        return () -> {
            if (CollectionUtils.isEmpty(context)) {
                MDC.clear();
            } else {
                MDC.setContextMap(context);
            }
            try {
                runnable.run();
            } finally {
                MDC.clear();
            }
        };
    }
}

b.下面定义一个ThreadPoolMdcExecutor 类来继承ThreadPoolTaskExecutor 类，重写execute和submit方法

import java.util.concurrent.Callable;
import java.util.concurrent.Future;
 
/**
 * @desc: 把当前的traceId透传到子线程特意加的实现。
 *   重点就是 MDC.getCopyOfContextMap()，此方法获取当前线程（父线程）的traceId
 */
public class ThreadPoolMdcExecutor extends ThreadPoolTaskExecutor {
    @Override
    public void execute(Runnable task) {
        super.execute(MdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
 
    @Override
    public Future<?> submit(Runnable task) {
        return super.submit(MdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
 
    @Override
    public <T> Future<T> submit(Callable<T> task) {
        return super.submit(MdcUtil.wrap(task, MDC.getCopyOfContextMap()));
    }
}

c.创建线程池Bean

    @Bean(name = "callBackExecutorConfig")
    public Executor callBackExecutorConfig() {
        ThreadPoolTaskExecutor executor = new ThreadPoolMdcExecutor();
        // 配置核心线程数
        executor.setCorePoolSize(10);
        // 配置最大线程数
        executor.setMaxPoolSize(20);
        // 配置队列大小
        executor.setQueueCapacity(200);
        // 配置线程池中的线程的名称前缀
        executor.setThreadNamePrefix("async-Thread-");
        // rejection-policy：当pool已经达到max size的时候，如何处理新任务
        // abort：在调用executor执行的方法中抛出异常 RejectedExecutionException
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
        // 执行初始化
        executor.initialize();
        return executor;
    }

2.对默认线程池进行增强

a.通过实现TaskDecorator 接口来增强线程池

public class ContextTransferTaskDecorator implements TaskDecorator {
    @Override
    public Runnable decorate(Runnable runnable) {
        Map<String, String> context = MDC.getCopyOfContextMap();

//        //子线程调用RequestContextHolder.currentRequestAttributes()会throw new IllegalStateException
//        //需要在执行子线程之前,在主线程中设置属性子线程共享
//        //ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
//        //RequestContextHolder.setRequestAttributes(servletRequestAttributes,true);
//        RequestAttributes requestAttributes = RequestContextHolder.currentRequestAttributes();
        return () -> {
            try {
                MDC.setContextMap(context);
//                RequestContextHolder.setRequestAttributes(requestAttributes);
                runnable.run();
            } finally {
                //防止线程内部MDC的内存泄漏,此处清除的是线程内部的MDC不影响主线程MDC信息
                MDC.clear();
//                RequestContextHolder.resetRequestAttributes();
            }
        };
    }
}

2.默认线程池的ThreadPoolTaskExecutor.setTaskDecorator

    @Bean(name = "callBackExecutorConfig")
    public Executor callBackExecutorConfig() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor ();
        // 配置核心线程数
        executor.setCorePoolSize(10);
        // 配置最大线程数
        executor.setMaxPoolSize(20);
        // 配置队列大小
        executor.setQueueCapacity(200);
        // 配置线程池中的线程的名称前缀
        executor.setThreadNamePrefix("async-Thread-");
        // rejection-policy：当pool已经达到max size的时候，如何处理新任务
        // abort：在调用executor执行的方法中抛出异常 RejectedExecutionException
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
        //线程池增强
        threadPoolTaskExecutor.setTaskDecorator(new ContextTransferTaskDecorator());
        // 执行初始化
        executor.initialize();
        return executor;
    }