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HttpContextAccessor 之singleton

2021-12-16 17:24  qgbo  阅读(308)  评论(0)    收藏  举报

HttpContextAccessor 在.Net 系统中生命周期是singleton。

每一个请求来的时候不是应该New 一个 Context 吗？

它的源码中用到了这个：AsyncLocal<int>

每一个线程会保存它的本地的值。相当于线程的内部变量。

下面代码会打印：

100,100,100
300,300,100
100,100,100
300,300,100

 var _local = 0;
            AsyncLocal<int> _asyncLocal = new AsyncLocal<int>();
            ThreadLocal<int>   _threadLocal= new ThreadLocal<int>();

Task.Run(() =>

{

Thread.Sleep(200);

while (true)

{

_asyncLocal.Value = 100;

_threadLocal.Value = 100;

_local = 100;

Thread.Sleep(2000);

Console.WriteLine(_asyncLocal.Value + $"   { _threadLocal.Value}  " + _local);

}

});


Task.Run(() =>

{

Thread.Sleep(200);

_asyncLocal.Value = 300;

_threadLocal .Value= 300;

_local = 300;

while (true)

{

Thread.Sleep(2000);

Console.WriteLine(_asyncLocal.Value + $"   { _threadLocal.Value}  " + _local);

}

});

Console.ReadLine();