Memory leak issue found in 8.0.4 Kubernetes C# Client SDK

[Moresoph]

Describe the bug
Kubernetes Csharp client has a memory leak problem when using the leader election functionality.

Kubernetes C# SDK Client Version
8.0.4

Server Kubernetes Version
Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.8", GitCommit:"83d00b7cbf10e530d1d4b2403f22413220c37621", GitTreeState:"clean", BuildDate:"2022-11-09T19:50:11Z", GoVersion:"go1.17.11", Compiler:"gc", Platform:"linux/amd64"}

Dotnet Runtime Version
.net 3.1 core

To Reproduce

Where do you run your app with Kubernetes SDK (please complete the following information):

• OS: Linux
• Environment container
• Cloud Azure

Additional context
Here is my investigation of this memory leak problem.
When we use the leader election functionality, we find that memory increases over time.

The following picture shows that the count of the object named "Linked1CancelaationTokenSource" increased greatly.

The following picture shows the call stack of how the KubernetesClient will call the function named "CreateLinkedTokenSource" to create the object named "Linked1CancelaationTokenSource".

The following picture shows the decompiled code from version 8.0.4 "KubernetesClient.Basic.dll". From the following decompiled code we can see, the "Dispose()" function of the "CancellationTokenSource cts" is not called.

[tg123]

the cts is not specific to leader election but every single rest call.

cancel after creates a timer in background and I do not think there is a way to cleanup it if wait is no longer available even calling dispose of cts.

however, I remember timer is very cheap obj in windows kernel.
from your screenshot, it is just 3MB

internal of cancelafter
https://github.com/dotnet/runtime/blob/b1a2080b9ce5833802fe2d632f79de6402097f14/src/libraries/System.Private.CoreLib/src/System/Threading/CancellationTokenSource.cs#L336

[Moresoph]

Hi tg123, thanks for your reply, you are right the cts is not specific to leader election. But actually, I don't get your point. The "cts" will not be disposed of by calling the "cts.CancelAfter(HttpClientTimeout)".

I did an experiment locally to test it. Here is the code:

Here is the managed memory:

The count of "CancellationTokenSource+Linked1CancellationTokenSource" is 50003, which shows that the "cts" will not be disposed of by calling the "cts.CancelAfter(10)".

Here is the process memory usage, the memory increased from 88M to 124M after creating 50000 "Linked1CancellationTokenSource".

I think we can solve this problem by just adding a "using" in front of this sentence "CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);"

[tg123]

double checked the .net src, you are right, dispose will clean up the timer.

[tg123]

could you please clone and test if the pr works?

[Moresoph]

Hi tg123, I am using version 8.0.4 now, It's hard for me to use the latest version because of the dependency version conflict. I don't know how to use your PR to build a version 8.0.4 client.

[tg123]

you can test with this nuget pkg https://github.com/tg123/csharp/pkgs/nuget/KubernetesClient/58619762

[Moresoph]

Hi tg123, Thanks very much. I will test with the nuget pkg you mentioned above.

[Moresoph]

Hi tg123, After executing this command "dotnet add package KubernetesClient --version 8.0.5", my project will add a 8.0.6 version, as the following picture shows. I don't know how to use the 8.0.5 version instead of the 8.0.6 version.

[tg123]

remove nuget.org, github source only
https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-nuget-registry#authenticating-with-a-personal-access-token

[Moresoph]

Hi tg123, Can you please tell me which version this memory leak problem started from? I know that version 5.0.4 don't have this issue. But after upgrading to version 8.0.4 this issue arises.
And another question is when will the new official pkg be released?

[tg123]

see #725