Lazy loading is not thread safe

[henriquewr]

Bug description

When acessing a lazy loading property that is kinda heavy do load (a lot of data in the db), and doing it with heavy concurrency, the lazy loader fails

sometimes the lazy loading property becomes null, and then after a short period of time it gets the value
and sometimes the lazy loader throw exeptions

Your code

I unfortly cant show the exact code because it's from my job, but it is basically that


var someEntity = _dbContext.SomeDbSet.FirstOrDefault();

var parallelOptions = new ParallelOptions { MaxDegreeOfParallelism = 1000 };
  Parallel.For(0, 60000, parallelOptions, i =>
  {
     var var1 =  someEntity.SomeLazyLoadICollection;
     var var2 =  someEntity.SomeLazyLoadICollection2;
     var var3 =  someEntity.SomeLazyLoadProp;
     var var4 =  someEntity.SomeLazyLoadICollection3;
     var var5 =  someEntity.SomeLazyLoadICollection4;
     var var6 =  someEntity.SomeLazyLoadICollection5;
  });

Stack traces

Verbose output

EF Core version

9.0.1

Database provider

Microsoft.EntityFrameworkCore.SqlServer

Target framework

.NET 9.0

Operating system

Windows 10

IDE

Visual Studio 2022 17.12.4