BackgroundService未关闭，stoppingToken从未与.net核心通用主机一起设置

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;

public class MyBackgroundService : BackgroundService
{
    private readonly IMyService _myService;
    private CancellationTokenSource _cancellationTokenSource;

    public MyBackgroundService(IMyService myService)
    {
        _myService = myService;
        _cancellationTokenSource = new CancellationTokenSource();
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        try
        {
            // 设置stoppingToken
            _cancellationTokenSource.CancelAfter(TimeSpan.FromSeconds(10));
            
            while (!stoppingToken.IsCancellationRequested)
            {
                // 执行后台任务
                await _myService.DoWork(stoppingToken);

                // 模拟后台任务的延迟
                await Task.Delay(TimeSpan.FromSeconds(1), stoppingToken);
            }
        }
        catch (OperationCanceledException)
        {
            // 在服务停止时执行清理工作
            await _myService.Cleanup();
        }
    }

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        // 停止BackgroundService时，取消任务并等待执行完成
        _cancellationTokenSource.Cancel();
        await Task.WhenAny(Task.Delay(TimeSpan.FromSeconds(5)), ExecuteAsync(cancellationToken));
    }
}