C# CancellationToken未导致引发OperationCanceledException

我想使用CancellationToken重新启动任务，以防它已经在运行。这是我的密码：

CancellationTokenSource cancellationTokenSource;
CancellationToken cancellationToken;

private void OnButtonCLick(object sender, RoutedEventArgs e)
{
    cancellationTokenSource?.Cancel();

    cancellationTokenSource = new CancellationTokenSource();
    cancellationToken = cancellationTokenSource.Token;

    Task.Run(() =>
    {
        try
        {
            while (true)
            {
                cancellationToken.ThrowIfCancellationRequested();
                Console.WriteLine("test");
                // ... calculation lasting few milliseconds ...
            }
        }
        catch (OperationCanceledException ex) { }
    }, cancellationToken);
}

由于某些原因，调用ThrowIfCancellationRequested时不会抛出OperationCanceledException。我将其与其他示例进行了比较，但没有发现这不起作用的原因。我做错了什么？

您的任务是读取cancellationToken字段，该字段将指向新的尚未取消的令牌。相反，您必须确保继续使用最初分配给任务的任务：

var token = cancellationToken;

Task.Run(() =>
{
    try
    {
        while (true)
        {
            token.ThrowIfCancellationRequested();
            Console.WriteLine("test");
            // ... calculation lasting few milliseconds ...
        }
    }
    catch (OperationCanceledException ex) { }
}, token);

您的任务是读取cancellationToken字段，该字段将指向新的尚未取消的令牌。相反，您必须确保继续使用最初分配给任务的任务：

var token = cancellationToken;

Task.Run(() =>
{
    try
    {
        while (true)
        {
            token.ThrowIfCancellationRequested();
            Console.WriteLine("test");
            // ... calculation lasting few milliseconds ...
        }
    }
    catch (OperationCanceledException ex) { }
}, token);