子线程无法共享主线程变量

后端接收http请求时,通过线程池异步处理：在子线程中发起feign接口请求，出现如下异常

Exception in thread "pool-2-thread-1" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.oauth2ClientContext': Scope 'request' is not active for the current thread; consider defining a scoped proxy for this bean if you intend to refer to it from a singleton; nested exception is java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.

Caused by: java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.

尝试添加让子线程共享主线程上下文的代码后，出现如下异常：

// 子线程继承主线程的上下文
RequestAttributes requestAttributes = RequestContextHolder.currentRequestAttributes();
RequestContextHolder.setRequestAttributes(requestAttributes, true);

Exception in thread "pool-2-thread-1" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.oauth2ClientContext': Scope 'request' is not active for the current thread; consider defining a scoped proxy for this bean if you intend to refer to it from a singleton; nested exception is java.lang.IllegalStateException: Cannot ask for request attribute - request is not active anymore!

Caused by: java.lang.IllegalStateException: Cannot ask for request attribute - request is not active anymore!

1、错误信息：上面抛错的信息，是在说http的request作用域就是在一次性的会话线程上，当回话结束的时候，会话线程也在不可用的状态，也就拿不到request上的属性信息了。主要你异步处理的时候，http的请求线程已经结束了导致的这个错误
2、你的想法是后端接收http请求时,通过线程池异步处理：在子线程中发起feign接口请求。我的一个想法是可用绕过线程变量同步的，后端接收http请求后把请求的数据都放到一个队列，线程池异步的消费这队列，再去在子线程中发起feign接口请求。希望这个想法对你有用。

本来通过线程池去获取调用线程的普通变量副本就有风险了，没搞好很容易出问题；
还在线程池里面去获取request信息，更会出问题，都异步了，前面的注线程很容易就先执行完，request就销毁了；
简单点在主线程里面把变量取出来，当做参数传递；

解决方案：在线程调用方法时当参数传递，之前线上有遇到这个问题，传递时也不能间接的获取，必须要直接给具体的值或者对象

3楼正解。多说一句，个人建议，多线程好好补下课。不管是子线程还是主线程还是孙子线程，都分别是不同的线程

查看FrameworkServlet源码如下:

默认是不允许类似RequestContextHolder这种上下文对象父子继承的, 如果想用可以自己更改对应设置:

但是需要注意官方的警告:

传参

定义公共变量，通过线程互斥的方式访问变量。

只能通过传参的方式，在线程调用方法的时候当参数传递

这个使用全局的变量试试

设置全局变量，传递参数即可