Analyzing .NET Core memory on Linux with LLDB

net-linux-memory

Most of the last week I’ve been experimenting with our .NET Windows project running on Linux in Kubernetes. It’s not as crazy as it sounds. We already migrated from .NET Framework to .NET Core, I fixed whatever was incompatible with Linux, tweaked here and there so it can run in k8s and it really does now. In theory.

In practice, there’re still occasional StackOverflow exceptions (zero segfaults, however) and most of troubleshooting experience I had on Windows is useless here on Linux. For instance, very quickly we noticed that memory consumption of our executable is higher than we’d expect. Physical memory varied between 300 MiB and 2 GiB and virtual memory was tens and tens of gigabytes. I know in production we could use much higher than that, but here, in container on Linux, is that OK? How do I even analyze that?

On Windows I’d took a process dump, feed it to Visual Studio or WinDBG and tried to google what’s to do next. Apparently, googling works for Linux as well, so after a few hours I managed learn several things about debugging on Linux and I’d like to share some of them today. Continue reading “Analyzing .NET Core memory on Linux with LLDB”

Quick intro to Docker

What’s Docker.

dockerOn the surface Docker looks like another virtual machine (VM). Just pick Ubuntu image with hello-world app inside, type docker run ubuntu hello-world  in your terminal of choice, and hello-world will start, thinking it owns a whole machine running Ubuntu.

But Docker is not a VM, manager of VMs, or hypervisor of any kind. Docker is a platform for creating, launching and managing containers. Those looks like VMs, quack like VMs, but are much closer to a fence with a barbwire on top of it. No app can enter, no app can leave. What is bad for humans works great for applications in production environment.

Because Docker doesn’t have to deal with guest operating system and hardware abstraction, it can work with the speed that VMs can only dream of, while doing quite similar job. Continue reading “Quick intro to Docker”