Local debugging? That’s easy. You’ve got your breakpoints, variable inspections, and on-the-fly state changes, provided you’ve got the right tools and know-how for your programming language.

But here’s a fun question: what if you hit a memory leak or a process crash a week into production? Even worse, in a complex system where recreating the issue is like finding a needle in a haystack. So, what do we do? Enter memory dumps.

What Are Memory Dumps?

Think of a memory dump like a snapshot of your app’s memory at the exact moment things went sideways – akin to a crime scene photo. Just as detectives piece together a case from a crime scene, developers dissect memory dumps to figure out what went wrong in the app. Hence, the term post-mortem debugging – self-explanatory, I’d say.

Memory dumps (or core dumps in Linux) are comprehensive: they reveal everything from variable values to the state of each thread in your application. It’s like hitting pause and delving deep into your app’s internals at the crucial moment.

Why Should We Care?

In production, memory dumps are like an airplane’s black box, providing crucial insights when standard debugging falls short. Here’s what a memory dump lets you do:

  • Pinpoint the root cause of crashes or memory leaks.
  • Grasp your application’s memory state before the meltdown.
  • Spot patterns or oddities that evade normal debugging. Also, spot interaction with the system-level things like drivers
  • For garbage-collected languages, diagnose memory fragmentation and view GC related information

Analyzing memory dumps can be daunting, but it’s a skill worth developing. I’ve written a post on starting with dump analysis in .NET. However, memory dumps and their tooling aren’t exclusive to .NET.

Here are some starting points for other languages:

What Do I Mean by ‘Tooling’?

So, you’ve got a production issue. Time to generate a memory dump. Different languages, different tools. For .NET, check out dotnet-dump. Node.js developers might prefer Chrome Dev Tools or the heapdump npm module.

Regardless of your environment, capturing a memory dump requires the right tools. Include these in your deployment process for hassle-free memory dump generation in production. For instance, deploying a .NET app in a Docker container? Don’t forget to add dotnet-dump and the relevant .NET SDK to your setup.

Series Roadmap

What’s Next?

In the next post of this series, we will take a look at the next ‘non-negotiable’ - comprehensive testing. Tests are crucial, and we will explore why.