Examining NodeJS core dump with llnode and lldb

Learning how to analyze .net core dumps on Linux with lldb and SOS plugin was really rewarding experience. It just feels good knowing that I can see managed stacks, objects and threads in something that looks very native and unmanaged. I saw there are also lldb plugins for Python and Java, but… can I do the same for NodeJS and JavaScript? Well,

OfCourse

There’s llnode plugin which does exactly that. Today I’m not going to go deeply into how it works – it’s not in the focus of my daily job now. But it’s still interesting to get a feeling of it. So, let’s dive right in. Continue reading “Examining NodeJS core dump with llnode and lldb”

The mystery of “Debug adapter process has terminated unexpectedly”

VS Code

Interesting story happened to me the other day. Visual Studio Code, my primary C# editor on Linux, suddenly stopped working. Well, it’s debugger did. Whenever I put a breakpoint and started debugging, nice friendly message would appear in the top of the editor, saying:

Debug adapter process has terminated unexpectedly

And it all worked just fine before. As recently I installed a whole bunch of new tools on my Ubuntu, such as lldb, perf and lttng, I played with removing and re-adding them again, reinstalling VS Code itself, but nothing seemed to help. Surprisingly, another C# IDE that supports Linux – JetBrains Rider – also failed to debug the projects I needed (worked fine with few others, though), so I had no other choice but try to get to the bottom of it, or at least make VS Code work again. Continue reading “The mystery of “Debug adapter process has terminated unexpectedly””

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”