Resources for Learning about .NET Internals

It all started with a tweet, which seemed to resonate with people:

The aim was to list blogs that specifically cover .NET internals at a low-level or to put it another way, blogs that answer the question how does feature ‘X’ work, under-the-hood. The list includes either typical posts for that blog, or just some of my favourites!

Note: for a wider list of .NET and performance related blogs see Awesome .NET Performance by Adam Sitnik

I wouldn’t recommend reading through the entire list, at least not in one go, your brain will probably melt. Picks some posts/topics that interest you and start with those.

Finally, bear in mind that some of the posts are over 10 years old, so there’s a chance that things have changed since then (however, in my experience, the low-levels parts of the CLR are more stable). If you want to double-check the latest behaviour, you’re best option is to read the source!

Community or Non-Microsoft Blogs

These blogs are all written by non-Microsoft employees (AFAICT), or if they do work for Microsoft, they don’t work directly on the CLR. If I’ve missed any interesting blogs out, please let me know!

Special mention goes to Sasha Goldshtein, he’s been blogging about this longer than anyone!!

Update: I missed out a few blogs and learnt about some new ones:

Book of the Runtime (BotR)

The BotR deserves it’s own section (thanks to svick to reminding me about it).

If you haven’t heard of the BotR before, there’s a nice FAQ that explains what it is:

The Book of the Runtime is a set of documents that describe components in the CLR and BCL. They are intended to focus more on architecture and invariants and not an annotated description of the codebase.

It was originally created within Microsoft in ~2007, including this document. Developers were responsible to document their feature areas. This helped new devs joining the team and also helped share the product architecture across the team.

To find your way around it, I recommend starting with the table of contents and then diving in.

Note: It’s written for developers working on the CLR, so it’s not an introductory document. I’d recommend reading some of the other blog posts first, then referring to the BotR once you have the basic knowledge. For instance many of my blog posts started with me reading a chapter from the BotR, not fully understanding it, going away and learning some more, writing up what I found and then pointing people to the relevant BotR page for more information.

Microsoft Engineers

The blogs below are written by the actual engineers who worked on, designed or managed various parts of the CLR, so they give a deep insight (again, if I’ve missed any blogs out, please let me know):


Finally, if you prefer reading off-line there are some decent books that discuss .NET Internals (Note: all links are Amazon Affiliate links):

All the books listed above I’ve bought copies of and read cover-to-cover, they’re fantastic resources.

I’ve also been recently recommend the 2 books below, they look good and certainly the authors know their stuff, but I haven’t read them yet:

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