IHostedServiceStartAsync调用随机，并导致错误的定时器间隔

在实现IHostedService时，可以考虑使用CancellationTokenSource来控制任务的取消。通过在StartAsync方法中创建CancellationTokenSource，并在StopAsync方法中取消该源，可以确保任务在需要时得到正确的取消。

示例代码：

public class MyService : IHostedService { private readonly CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();

public Task StartAsync(CancellationToken cancellationToken)
{
    // Use our own CancellationTokenSource so we can guarantee our task will be cancelled if desired
    var task = DoWork(_cancellationTokenSource.Token);
    return Task.CompletedTask;
}

public async Task StopAsync(CancellationToken cancellationToken)
{
    // Cancel our CancellationTokenSource, which will in turn cancel our task
    _cancellationTokenSource.Cancel();
    await Task.CompletedTask;
}

private async Task DoWork(CancellationToken cancellationToken)
{
    while (!cancellationToken.IsCancellationRequested)
    {
        // Perform work here
        await Task.Delay(TimeSpan.FromSeconds(10), cancellationToken);
    }
}

}