[Win11] [Bug] [ConcurrentBag regression in .Net 9] System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

[drweb86]

Steps:

1. Create new .Net 9 project and put code in Visual Studio 2022

using System.Collections.Concurrent;

var breakingBadHoleInTheBag = new ConcurrentBag<ConcurrentBagItem>();

int tries = 500000;
while (tries-- > 0)
{
    breakingBadHoleInTheBag.SingleOrDefault(x => x == (object)breakingBadHoleInTheBag);
    breakingBadHoleInTheBag.Add(new ConcurrentBagItem());
}

class ConcurrentBagItem { }

2. Execute with or without debugger

Actual result:

An unhandled exception of type 'System.AccessViolationException' occurred in System.Collections.Concurrent.dll
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Expected result:

Works without error, as in .Net 9.

Please introduce ConcurrentBag - from .Net 8 because uinstable work in .Net 9 breaks my app

[drweb86]

If to go through stack trace - System.Linq is third one, Ion double click on it VIsual Studio 2022 crashes (!).

[ViktorHofer]

@dotnet/area-system-collections

[stephentoub]

It's very unlikely this is actually related to ConcurrentBag. It's more likely some code in your app is resulting in corruption that then appears as an AV in other code, in this case in CB. Without a repro or crash dump, though, we can't investigate.