Request Batching Database Context Scoping

[tnc1997]

Product

Hot Chocolate

Version

15.1.3

Link to minimal reproduction

https://github.com/tnc1997/hot-chocolate-request-batching

Steps to reproduce

git checkout v15
docker compose up --build --detach
curl http://localhost:5135

What is expected?

The blogs and posts should be added to the database without any exceptions being thrown.

What is actually happening?

The blogs and posts are not being completely added to the database (some are failing).

Relevant log output

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.","stackTrace":"   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()\n   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()\n   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)\n   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)\n   at Server.Mutation.AddPostAsync(BloggingContext context, ILogger`1 logger, Guid id, String title, Guid blogId, CancellationToken cancellationToken) in /src/Server/Types.cs:line 86\n   at HotChocolate.Resolvers.Expressions.ExpressionHelper.AwaitTaskHelper[T](Task`1 task)\n   at HotChocolate.Types.Helpers.FieldMiddlewareCompiler.<>c__DisplayClass9_0.<<CreateResolverMiddleware>b__0>d.MoveNext()\n--- End of stack trace from previous location ---\n   at HotChocolate.Types.MutationConventionTypeInterceptor.<>c__DisplayClass16_0.<<ApplyResultMiddleware>b__1>d.MoveNext()\n--- End of stack trace from previous location ---\n   at HotChocolate.Types.MutationConventionMiddleware.InvokeAsync(IMiddlewareContext context)\n   at HotChocolate.Types.ErrorMiddleware.InvokeAsync(IMiddlewareContext context)\n   at HotChocolate.Execution.Processing.Tasks.ResolverTask.ExecuteResolverPipelineAsync(CancellationToken cancellationToken)\n   at HotChocolate.Execution.Processing.Tasks.ResolverTask.TryExecuteAsync(CancellationToken cancellationToken)

Additional context

The v13 branch works as expected however the v14 branch and the v15 branch have issues with multiple operations being performed concurrently using the same database context when batching requests.

[michaelstaib]

That is by design .... Batching will execute operations in parallel and share between these requests a DataLoader context ...
Each async field has its own DI context that can work in isolation. We have a series about the new Data APIs here:
https://www.youtube.com/@chillicreamtv

[tnc1997]

Each async field has its own DI context that can work in isolation.

Excuse my naivety but does this isolation mechanism apply to both queries and mutations?

Was this a change introduced from version 13 to 14?