dotnet-gcdump issues on .NET 8

[kwiatkos0]

Describe the bug

We are encountering an issue with dotnet gcdump on .NET 8 (runtime 8.0.11). When attempting to capture dumps from an app hosted in Kubernetes, the first dump works correctly. However, subsequent dumps contain UNKNOWN object types.

Related issues:

• Lots of uknown objects with .net core 2.x microsoft/perfview#866
• dotnet-gcdump and perfview's gcdump do not work on 5.0 runtimes runtime#38639

To Reproduce

Code used to install the SDK and gcdump tool:

wget https://download.visualstudio.microsoft.com/download/pr/40bc5873-1a39-4a47-9df5-b481869594a6/8455eab2092cc1321ac055f016ef90cf/dotnet-sdk-6.0.404-linux-x64.tar.gz
mkdir -p $HOME/dotnet && tar zxf dotnet-sdk-6.0.404-linux-x64.tar.gz -C $HOME/dotnet
export DOTNET_ROOT=$HOME/dotnet
export PATH=$PATH:$HOME/dotnet
cd $HOME/dotnet
./dotnet tool install --global dotnet-gcdump
export PATH="$PATH:/root/.dotnet/tools"
dotnet-gcdump -p 1 -v

We tried different .NET SDK versions on various Kubernetes pods:

• 8.0.11 https://download.visualstudio.microsoft.com/download/pr/71b9adff-5d7d-4567-aba4-d0da010e293f/88bd38320ab4a4524e71aec64bf88676/dotnet-sdk-8.0.111-linux-x64.tar.gz
• 6.0.404 https://download.visualstudio.microsoft.com/download/pr/40bc5873-1a39-4a47-9df5-b481869594a6/8455eab2092cc1321ac055f016ef90cf/dotnet-sdk-6.0.404-linux-x64.tar.gz
• 8.0.404 https://download.visualstudio.microsoft.com/download/pr/4e3b04aa-c015-4e06-a42e-05f9f3c54ed2/74d1bb68e330eea13ecfc47f7cf9aeb7/dotnet-sdk-8.0.404-linux-x64.tar.gz
  We also tried different dotnet-gcdump versions:
• 9.0.553101
• 8.0.547301
• 8.0.532401
• 6.0.351802

All attempts resulted in UNKNOWN object types on the second and subsequent dumps.

When testing on a service still running .NET 6 (runtime 6.0.31, SDK 6.0.404, gcdump 6.0.351802), everything worked as expected.

Exceptions (if any)

The gcdump file contains invalid objects:

Error: Did not have a type definition for typeID 0x7efbc53bed60
Error: Did not have a type definition for typeID 0x7efbc539e458
Error: Did not have a type definition for typeID 0x7efbc539eb28
Error: Did not have a type definition for typeID 0x7efbc539ec50
Error: Did not have a type definition for typeID 0x7efbc539f5b8
Error: Did not have a type definition for typeID 0x7efbc539f7a0
Error: Did not have a type definition for typeID 0x7efbc539f8d8
Error: Did not have a type definition for typeID 0x7efbc539f9b0

Further technical details

• Include the output of dotnet --info
• The IDE (VS / VS Code/ VS4Mac) you're running on, and its version

Host:
  Version:      8.0.11
  Architecture: x64
  Commit:       9cb3b725e3
  RID:          linux-x64

.NET SDKs installed:
  No SDKs were found.

.NET runtimes installed:
  Microsoft.AspNetCore.App 8.0.11 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 8.0.11 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  DOTNET_ROOT       [/root/dotnet]

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

[marcpopMSFT]

This should be transferred to the dotnet/diagnostics repo but I apparently don't have permissions. @hoyosjs do you have permissions?