手动取消并释放Task资源

用取消令牌取消Task

• CancellationTokenSource:取消令牌
• cancellationTokenSource?.Cancel();：其中？表示判断cancellationTokenSource是否为null,如果不是null才取消，否则会造成找不到实例的异常
• 当!cancellationToken.IsCancellationRequested后则不再进入While循环中，最后等待Thread.Sleep(2000);后Task资源被释放。

internal class Class1
{
    private CancellationTokenSource cancellationTokenSource;
    public void CancelTask()
    {
        cancellationTokenSource?.Cancel();
    }

    public void process()
    {
        cancellationTokenSource = new CancellationTokenSource();
        CancellationToken cancellationToken = cancellationTokenSource.Token;

        Task.Run(() =>
        {
            while (!cancellationToken.IsCancellationRequested)
            {
                Thread.Sleep(1000);
            }
            Thread.Sleep(2000);
        });
    }
}