如何在DBContext上同时执行多个操作？

发布于 2025-02-06 18:35:12 字数 1652 浏览 1 评论 0原文

我有以下背景服务运行：

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            await Task.Run(async () =>
            {
                while (!stoppingToken.IsCancellationRequested)
                {
                    using (var scope = _scopeFactory.CreateScope())
                    {
                        DataContext dbContext = scope.ServiceProvider.GetRequiredService<DataContext>();
                        var tasks = new List<Task>();
                        tasks.Add(siteA.ProcessSchedule(SportLeagues.MLB, logger, dbContext));
                        tasks.Add(siteB.ProcessSchedule(SportLeagues.MLB, logger, dbContext));
                        //....more of same task
                        await Task.WhenAll(tasks);
                        await dbContext.SaveChangesAsync();
                        await Task.Delay(0, stoppingToken);
                    }
                }
            });
        }

我不断获得此错误

System.InvalidOperationException: 
    A second operation was started on this context instance before a previous operation completed.

，我可以为每个任务进行重构并创建一个dbContext，但是如果可能的话，我更喜欢使用单个dbcontext。

我还尝试将我的dbcontext添加为瞬态：

builder.Services.AddDbContext<DataContext>(options =>
{
    options.UseInMemoryDatabase("db");
}, ServiceLifetime.Transient);

但这无济于事。我是否以不正确的方式创建了我的dbcontext？还是为每个任务创建新的dbContext的最佳方法？对于更多上下文，这是一个不断运行的背景任务，需要一秒钟才能完成，并且将拥有大约20个任务。每秒创建和破坏20 dbContext，以及必须执行20 dbContext Saves，听起来很低。

原文

I have the following background service running:

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            await Task.Run(async () =>
            {
                while (!stoppingToken.IsCancellationRequested)
                {
                    using (var scope = _scopeFactory.CreateScope())
                    {
                        DataContext dbContext = scope.ServiceProvider.GetRequiredService<DataContext>();
                        var tasks = new List<Task>();
                        tasks.Add(siteA.ProcessSchedule(SportLeagues.MLB, logger, dbContext));
                        tasks.Add(siteB.ProcessSchedule(SportLeagues.MLB, logger, dbContext));
                        //....more of same task
                        await Task.WhenAll(tasks);
                        await dbContext.SaveChangesAsync();
                        await Task.Delay(0, stoppingToken);
                    }
                }
            });
        }

I constantly get this error

System.InvalidOperationException: 
    A second operation was started on this context instance before a previous operation completed.

I can refactor and create a dbContext for each task, however I would prefer to use a single dbContext if possible.

I also tried adding my dbContext as transient:

builder.Services.AddDbContext<DataContext>(options =>
{
    options.UseInMemoryDatabase("db");
}, ServiceLifetime.Transient);

But this did not help. Am I creating my dbContext in an incorrect way? Or is the best approach to create a new dbContext for each task? For more context, this is a constantly running background task, it takes a second to complete and it will have around 20 tasks. It sounds pretty inefficient to be creating and destroying 20 dbContext every second, along with having to do 20 dbContext saves.

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