Multi-threading exception System.InvalidOperationException in the BlazorWebAppMovies sample.

[MagistratasHK]

Describe the issue

The 8.0\BlazorWebAppMovies sample (presumably 9.0 too) throws an exception System.InvalidOperationException in the Pages/MoviewPages/Index.razor component if the titleFilter search box is changed in quick succession. The error is due to multiple input events running on different threads on the same circuit passing the same context to the QuickGrid, which runs queries asynchronously while EF Core does not support it.

To Reproduce

1. Initialize the database with large number of movie records to introduce some load and delay.

for (int i = 0; i < 50000; i++)
{
    context.Movie.Add(
        new Movie
        {
            Title = $"Movie #{i:00000}",
            ReleaseDate = new DateOnly(Random.Shared.Next(1970, 2025), Random.Shared.Next(1, 13), Random.Shared.Next(1, 29)),
            Genre = "Test",
            Price = Convert.ToDecimal(Random.Shared.Next(1, 5)),
            Rating = "NR"
        }
    );
}

1. Go to the 'Movies' index page.
2. Quickly type some text in the search box.
3. Observe an exception.

Expected behavior

The grid should handle quick typing in the search box.

Exception

fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred while iterating over the results of a query for context type 'BlazorWebAppMovies.Data.BlazorWebAppMoviesContext'.
      System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
      System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
      Unhandled exception rendering component: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
      System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
         at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.ResolveItemsRequestAsync(GridItemsProviderRequest`1 request)
         at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.RefreshDataCoreAsync()
         at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
      Unhandled exception in circuit 'T40BpmO-meEOigVitZBZSUulErKT01iXsm_-RWKhVVI'.
      System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
         at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.ResolveItemsRequestAsync(GridItemsProviderRequest`1 request)
         at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.RefreshDataCoreAsync()
         at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
      Unhandled exception rendering component: Encountered unsupported frame type during diffing: None
      System.NotImplementedException: Encountered unsupported frame type during diffing: None
         at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
         at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
         at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
         at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
         at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
         at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

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Issue Details

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• Content Source: dotnet/blazor-samples
• GitHub Login: @guardrex

[guardrex]

Hello @MagistratasHK ... Open this for the product unit at ...

https://github.com/dotnet/aspnetcore/issues

Please add ...

cc: @guardrex https://github.com/dotnet/blazor-samples/issues/480

... to the bottom of your opening comment so that I can follow along. I might re-open this for doc work depending on what they say.

[guardrex]

I've moved this over to dotnet/AspNetCore.Docs#34881 for work. I'll add a section for now to the QuickGrid article, and I'll probably be able to version that section out at 10.0 when they fix the underlying issue with the items provider.