【C#】【多线程】【05-使用C#6.0】06-避免使用捕获的同步上下文

```csharp
/// <summary>
/// 避免使用捕获的同步上下文
/// </summary>
/// <param name="args"></param>
[STAThread]
static void Main(string[] args)
{
    var app = new Application();
    var win = new Window();
    var panel = new StackPanel();
    var button = new Button();

_label = new Label();
    _label.FontSize = 32;
    _label.Height = 200;

button.Height = 100;
    button.FontSize = 32;
    button.Content = new TextBlock { Text = "开始异步操作" };
    button.Click += Click;

panel.Children.Add(_label);
    panel.Children.Add(button);

win.Content = panel;
    app.Run(win);

Console.ReadLine();
}

private static Label _label;

static async void Click(object sender, EventArgs e)
{
    _label.Content = new TextBlock { Text = "计算中......" };
    TimeSpan resultWithContent = await Test();
    TimeSpan resultNoContent = await TestNoContent();
    //TimeSpan resultNoContent = await TestNoContent().ConfigureAwait(false);

_label.Content = new TextBlock { Text = sb.ToString() };
}

static async Task<TimeSpan> Test()
{
    const int iterationsNumber = 100000;
    var sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < iterationsNumber; i++)
    {
        var t = Task.Run(() => { });
        await t;
    }
    sw.Stop();
    return sw.Elapsed;
}

static async Task<TimeSpan> TestNoContent()
{
    const int interationsNumber = 100000;
    var sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < interationsNumber; i++)
    {
        var t = Task.Run(() => { });
        // 将continueOnCapturedContext指定为false，不使用捕获的同步上下文运行后续操作代码
        await t.ConfigureAwait(continueOnCapturedContext: false);
    }
    sw.Stop();
    return sw.Elapsed;
}
```

运行结果：

```
With the content: 00:00:04.5821377
Without the content: 00:00:02.4224249
Ratio: 1.89
```

如果在运行时不停的改变窗体大小，运行结果的比率会显著的变大：

```
With the content: 00:00:16.0775755
Without the content: 00:00:03.2937352
Ratio: 4.88
```

【C#】【多线程】【05-使用C#6.0】06-避免使用捕获的同步上下文

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