Abhinav Upadhyay (@abhi9u) / X

Abhinav Upadhyay

14.8K posts

Abhinav Upadhyay

@abhi9u

NetBSD Dev | Python Internals, AI, compilers, databases, & performance engineering | Join 16k+ other readers at blog.codingconfessions.com

blog.codingconfessions.com

Joined July 2009

Pinned
Abhinav Upadhyay
@abhi9u
May 31
A quick update on the Ebook: - I've updated the PDF with better styling - great to read on devices. - And, there is also an EPUB version available now.
Abhinav Upadhyay
@abhi9u
May 16
Before jumping into books like DDIA or Database Internals, it helps to understand the systems layer these designs are built on. A lot of the design of such data-intensive systems is based on virtual memory: page tables, page faults, mmap, the page cache, swapping, NUMA
12K
Abhinav Upadhyay
@abhi9u
Jan 18, 2025
How do you fit a 250kB dictionary in 64kB of RAM and do lookups? For reference, even gzip -9 cannot compress this file beyond 85kB. In the 1970s, Douglas McIlroy at AT&T had the same challenge when implementing the spell checker for Unix. Instead of relying on generic
355K
Abhinav Upadhyay
@abhi9u
May 21, 2025
I see possibilities.
287K
Abhinav Upadhyay
@abhi9u
Apr 5, 2025
This hits hard. I've struggled to make it on substak because of all the crazy RBI regulations. So crazy that stripe left India. Receiving money for any consulting gig directly in the bank requires explaining five people at the bank why that transaction happened. Getting GST is
Mahima Jalan ماهيما جالان
@MahimaJalan2
Apr 5, 2025
After finishing my Master’s in Journalism, I decided to start my own agency and create jobs instead of working for someone else. But soon after, I got a serious reality check. My GST application was rejected, not due to any issue in paperwork, but because the officers
291K
Abhinav Upadhyay
@abhi9u
Mar 6, 2025
Everyone recommends reading research papers, but few talk about how to do it effectively. Like any skill, it gets easier with time, but starting out can be daunting. It helps to know that the struggles you face are common, and that there are ways to overcome them. I wrote about
245K
Abhinav Upadhyay
@abhi9u
Dec 7, 2023
"a + b", this one line of Python code executes thousands of lines of C behind the scenes. My latest article explains what goes on in the CPython runtime to execute this seemingly simple operation. You will learn about: - Dynamic dispatch implementation in CPython - What is the
Abhinav Upadhyay
@abhi9u
Dec 5, 2023
The next article in the CPython internals series is ready (pending edits). It stands at 1800 words & 13 annotated code listings. All that just to explain, what goes on when you run `a + b` in Python. Coming soon to the subscribers of Confessions of a code Addict (link in bio).
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Abhinav Upadhyay
@abhi9u
Apr 14, 2025
Some of the best engineers I’ve met share one thing in common. They don’t just learn how a system works. They understand why it was built that way. That kind of understanding doesn’t come from scrolling past summaries or skimming neatly labeled diagrams. But that’s how a lot of
131K
Abhinav Upadhyay
@abhi9u
Aug 26, 2024
This looks like an excellent course on computer architecture from ETH Zurich. It seems specifically focused on memory and very up-to-date wrt what is being used in the industry:
222K
Abhinav Upadhyay
@abhi9u
Dec 26, 2024
You thought systems programmers don't need to know math? Linux kernel developers prove you wrong by contradiction—they prove corollaries in their comments.
115K
Abhinav Upadhyay
@abhi9u
Aug 10, 2025
The point that Linus makes is right but his style is not. It sets the wrong precedent for the younger generation to be just as toxic as this. You can criticise the code without being abusive. I've seen enough quotes saying this is based, it is not. If I tell my colleague I will
The Lunduke Journal
@LundukeJournal
Aug 9, 2025
Today, Linus Torvalds told a Google engineer that his code (updating RISC-V support in the Linux kernel) is “garbage” which “makes the world actively a worse place to live”. Adding that the Google engineer’s code needs to “get bent”. As you might have guessed, Torvalds has
245K
Abhinav Upadhyay
@abhi9u
Dec 8, 2024
What every systems programmer should know about concurrency—a very dense but impactful read. Things like lock free and wait free synchronisation techniques will stop seeming like black box if you understand this.
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Abhinav Upadhyay
@abhi9u
Sep 20, 2023
Turns out folding a piece of paper in specific ways can result in a Turing complete device open.techwriters.info/apieceofthepi/…
203K
Abhinav Upadhyay
@abhi9u
Dec 6, 2024
Book recommendation: Understanding the Linux kernel. Very few books on operating systems provide this level of depth. It is very specific to X86 and that too 32 bit, but still many details are still relevant. The kernel code has also changed significantly in these 20 years but
116K
Abhinav Upadhyay
@abhi9u
Nov 6, 2023
To lighten up your Monday
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