.NET Core 3.1 running in GAE Flex - Thread Pool Starvation

[Tony Colant]

I have .NET Core 3.1 MVC app running in GAE Flex that periodically experiences slowness then eventually becomes unresponsive.  When I look in the logs I see  Microsoft.AspNetCore.Server.Kestrel[22]  and thread starvation errors.  The following is a recent example:

The app can run weeks/months without issue.  Many times, the app is idle (no users) for long periods of time (hours) as shown in the logs then the thread starvation errors start appearing.

When looking at the dashboard, CPU usage, Instances, Memory usage, etc are all normal and not overworked or auto scaled up to accommodate (the app.yaml is configured to auto scale).  

This is the only GAE Flex app in the project though there are 2 Node.js apps that run in GAE Standard in the same project.

It's almost as if there's something else on the VM or the physical metal that's consuming threads and causing my app to fail.

Bouncing the service resolves the issue.

Since this is so sporadic, it's hard to diagnose.  

Any suggestions/pointers are appreciated...

Thanks,

TC

[Shawn Wu]

I have confirmed there is no recently update for flexible environment for .NET[1].

The issue seems to be specific impact your service,  I recommend you to open an support case, allowing support team to investigate further.

[1] https://cloud.google.com/appengine/docs/flexible/dotnet/release-notes