WindowsFormsSynchronizationContext.Current.Post在后台线程执行的lambda [英] WindowsFormsSynchronizationContext.Current.Post executes lambda on background thread

问题描述

在发布lambda表达式的电流 WindowsFormsSynchronizationContext ，我发现拉姆达代码执行在后台线程：

When posting a lambda expression to the current WindowsFormsSynchronizationContext, I find that the lambda code executes on a background thread:

// running on main thread here

myLabel = new Label();
this.Controls.Add(myLabel);

WindowsFormsSynchronizationContext.Current.Post( ignore => {

    // returns true !
    bool invokeRequired = myLabel.InvokeRequired; 

    // returns a background thread, not the UI thread
    int threadId = System.Threading.Thread.CurrentThread.ManagedThreadId; 

    // throws, because we are (unexpectedly) on a background, different thread
    myLabel.Text = "whatever";

},null);

此外， WindowsFormsSynchronizationContext.Current 似乎并不返回 WindowsFormsSynchronizationContext ，而是一个普通的 System.Threading.SynchronizationContext 。

Besides, WindowsFormsSynchronizationContext.Current does not seem to return a WindowsFormsSynchronizationContext, but rather an ordinary System.Threading.SynchronizationContext.

这是突然发生的事情是用于没有螺纹的问题，并没有被最近修改（解决方案的其他部分都）在窗体上。我试图寻找出明显的错误（如在后台线程创建，代码实例化在后台线程的形式本身，或控件），但我一直没能找到显著的违规行为。

This is suddenly happening on a form that used to have no thread problems and hasn't been recently modified (other parts of the solution were). I have tried looking for obvious mistakes (such as, code that instantiates the form itself on a background thread, or controls created on a background thread) but I haven't been able to find significant violations.

也许我期待在错误的方向？

Perhaps I am looking in the wrong direction?

推荐答案

WindowsFormsSynchronizationContext.Current 相同 SynchronizationContext.Current 。你应该让你通过一个派生类中调用基静态成员编译器警告。

WindowsFormsSynchronizationContext.Current is the same as SynchronizationContext.Current. You should be getting a compiler warning that you are invoking a base static member through a derived class.

检查 SynchronizationContext.Current.GetType（），你会发现，你是一个不同的同步上下文中运行。

Check SynchronizationContext.Current.GetType() and you'll find out that you are running under a different sync context.

夺UI线程上正确的上下文并储存起来。

Capture the correct context on the UI thread and store it.

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