Jon Gjengset

My talk from Rust Munich two weeks ago arguing for why comments are good actually is now up! youtu.be/Ke3PYexY6XE?...

I got a 2-meow server rack. Highly recommend.

Recording of yesterday's open source maintenance stream is now up! We got through left-right (a concurrency primitive), HdrHistogram (a fun data structure), rust-imap (you guessed it), and inferno (the Rust port of flamegraph) in about 5 hours — OSS is no joke 😅 youtu.be/bAINppA0BSU

Haven't done an open source maintenance stream in a while, and by now I have a few open open-source issues and pull requests I'm behind on, so let's rectify that! Stream will be this Saturday at 1pm UTC on youtube.com/live/7h7ciBk... — see you there!

After the AI Engineer conference, which was full of useful criticism, I remembered that the most confident takes on AI often came from the least exposure. Rejection is easy, trial and error is expensive. I wrote about it. lucumr.pocoo.org/2026/4/11/th...

Recording of yesterday's stream implementing a WAV noise file generator in #rust is now up on YouTube! We managed to get white, pink, brownian, blue, violet, and grey (psychoacoustic!) noise all implemented, so I'll count that as a success 🔊 youtu.be/zOTE4BN59u4

A few weeks ago I was interviewed by Daniel from Rock the JVM, a channel (unsurprisingly) for folks in the JVM ecosystem. It was fun to chat about Rust with someone "from the outside", and if you want to hear it, it's now up on his YouTube channel! youtu.be/Cg8gASzqqOs?...

The past few streams have been pretty high level, but not this time! Friday at 4p UTC (everytimezone.com?t=69cf0300,3c0), we're going back down to "what bits go where". We'll try to write an audio generator that produces WAV files with white/pink/brown noise by hand 🔊 youtube.com/live/BKHE7st...

Back in January I gave a talk at Jane Street titled "Are Mutexes Slow?" (I gave a lightning version of it at @rustikon.dev last week!). And it's now up on YouTube if you're interested in wonky details about CPU cache coherence and the cost of coordination! www.youtube.com/watch?v=tND-...

Sadly I can't make it to the inaugural TokioConf (Portland, Apr 20-22), but I do have a 15% off code I've been told to hand out to people excited to go! So, if you've been on the fence, ping me and I'll see what I can do! More on the conf & who it's for (most people!) here: tokio.rs/blog/2026-03...

In January, @anishathalye.bsky.social, @josejg.bsky.social, and I returned to @csail.mit.edu to teach Missing Semester, a class on topics we miss from most CS programs—tools and techniques that everyone should know, like Bash, Git, CI, and AI tools. Today, we’re releasing the course for free online!

Recording of our "port avro-tools' Java-based idl-to-json tool to Rust using an LLM" adventure is now on YouTube! We got to an initial working implementation in ~4hrs (though still bugs to iron out in future iterations), which isn't too shabby! Code at github.com/jonhoo/avdl. youtu.be/vmKvw73V394

The recording of the new year's Q&A stream is now up, with all the questions annotated for easy skipping! youtu.be/S_zp82fYrGw

Quick reminder that this is coming up. Lots of good questions have come in, so please take some time to go in and vote for the ones you care the most about!

Okay, this is pretty cool.

Video of the One Billion Row Challenge stream is now up at youtu.be/tCY7p6dVAGE! We got down to 1.2s without any external dependencies, and it was a fun journey down lots of performance rabbit holes (only some of which panned out 😅). It is over 10h, but hopefully the chapters in the video help!

On Sunday at 2pm UTC (everytimezone.com?t=68fd6480,348), Ben and I are doing another "What's New in Rust" marathon stream for Rustacean Station! I'm guessing ~5h for part 1 😅 It'll be over at youtube.com/live/6mwVWmK.... Come join us 📺🎉

In August, I was interviewed by JetBrains about programming and Rust, ranging from the borrow checker, to agentic coding, to hiring. And it's now on YouTube! It's also general enough that it should be interesting even to those not already knee deep in Rust 😅 www.youtube.com/watch?v=nOSx...

About a month ago, I gave a talk at the Rust Amsterdam meetup about Sguaba (the type-safe spatial math Rust crate), and the recording of that is now online for anyone who wants their head to hurt with frames of reference and coordinate transforms 😅 youtu.be/kESBAiTYMoQ

For those who missed the stream, you can find my chat with Maya about Rust, concurrency, left-right, Noria, career development, AI, and a whole host of other random nerdy things on YouTube now! www.youtube.com/live/kJnrbbt...

Sunday at 6pm UTC (everytimezone.com/s/4a616697), I'll be on Maya Rainer's stream to talk about concurrency and the left-right crate. We'll take a bunch of questions from chat, so bring your burning `Send + Sync` questions :D Stream will be over at www.twitch.tv/mayarainer/s... — see you there!

For those curious about the third proposed Sguaba feature, I ended up writing it myself and having Claude suggest tests. Worked quite well! Given the nuances in designing this mechanism, I suspect it would have struggled quite a lot with implementing it from scratch 😅 github.com/helsing-ai/s...

Missing Semester has grown past 100K subscribers on YouTube. Appreciate all the engagement and support! We plan to teach another iteration of the course in January 2026, revising the curriculum and covering new topics like AI IDEs and vibe coding.

Today's "vibe-code non-trivial changes to a Rust crate" stream is up! Got to 2/4 changes and then ran out of tokens on the Claude Pro plan 😅 Still TBD if my Luddite skepticism is apt, but it was fun, interesting, and did shed light on the ups and downs of agentic Rust coding! youtu.be/EL7Au1tzNxE

Change of plans — due to the ongoing heatwave in Oslo, and Norway's general lack of A/C, my office is regularly reaching 32°C/90°F these days. This breaks my brain, and also my camera, so I'm going to move this stream to the same time next week! See you then 👋

The other day I was interviewed about Helsing, working in defense, and what it's like specifically to work at Helsing. We ended up covering quite a lot of questions I commonly get (and that I know people have but don't ask), so if you're curious about any aspect of it, give it a read!

If you happen to be in Amsterdam at the end of July, come stop by the Amsterdam Rust meetup, where I'll be talking about the rigid body transform crate Sguaba! meetu.ps/e/Pbn87/z2g5...

A bit of a long shot: the regular audio editor for the "What's New" Rustacean Station episodes is now busy with other life stuff. The last episode I edited myself, but it took ages! Anyone know an editor (ideally familiar with Rust, but not a requirement) who'd take on a regular (paid) editing gig?

Question: if I end up doing more "play to learn"/"teach by playing" (name still tbd) streams on tech-but-not-Rust topics, would you all prefer for it to be on the same YouTube channel, a separate one, or does it not matter?

SHENZHEN I/O stream where I try to teach some assembly by playing an assembly-inspired game is now up! This is very much an experiment, so please let me know if this format was still entertaining + educational :) youtu.be/zycRrVS3NLc

For those who watched live from the beginning 😂 Not to worry, that part is cut out from the non-live version, but entertaining nonetheless.