lucky husband, proud papa, @BLAKE3team, really into Rust, Keybase SpaceX alum, currently @astral_sh

Joined September 2014
125 Photos and videos
Pinned Tweet
My latest blog post is about a class of deadlocks that comes up in async Rust: jacko.io/snooze.html

2
10
721
Jack O'Connor retweeted
Friday Facts #441 - Space logistics improvements factorio.com/blog/post/fff-4…
9
33
376
14,143
Jack O'Connor retweeted
I was recently diagnosed with a rare autoimmune disorder called anti-NMDA receptor encephalitis. It's a "disease of chaos" that completely upturned my life for a couple months. I wrote a blog about it that goes into more detail and discusses prognosis. burntsushi.net/encephalitis/

34
84
405
51,900
Jack O'Connor retweeted
11
154
3,372
100,980
Jack O'Connor retweeted
Replying to @SciGuySpace
I am hesitant to get ahead of a proper data review, but I understand the space community’s curiosity, especially when imagery can give the impression of a problem. As you would expect, engineers were eager to inspect the heat shield, starting with diver imagery shortly after splashdown and continuing with the review aboard the ship. No unexpected conditions were observed. I suspect when the images are released, it will be pretty obvious the stark difference between Artemis I and Artemis II head shield performance. As to the question specifically, the discoloration was not liberated material. The white color observed corresponds to the compression pad area and is consistent with the local geometry, AVCOAT byproducts, and transitional heating environments. We observed this behavior in arc jet testing and expected it in this compression pad area. We will complete a full data review across all systems, including the thermal protection system, and make the results publicly available.
207
907
17,402
894,969
Jack O'Connor retweeted
Been at ESPN a long time - this one was an all timer. Before social media, it was as viral as a story can be. I watched it on a tape in the news room. I couldn’t stop watching his teammates.
504
3,888
40,595
4,206,145
Jack O'Connor retweeted
This math joke is nice. Happy pi day.
139
2,474
28,294
679,427
Jack O'Connor retweeted
Replying to @LinkofSunshine
The three kinds of stock market day so far this month: - Donald Trump spins the Wheel O' Tariffs and replaces 5% tariff on Belarussian wheat with 22.4% tariff on Pakistani jet engines. All stocks lose 2d6 dollars. - Substack newsletter publishes story about DoorDash doing badly. DoorDash down 862%, global financial system teeters on the brink. - NVIDIA announces earnings of one hundred trillion dollars, beating expectations by 1,000x. Jensen Huang named new king of Earth, with his stockholders to form the new permanent ruling class. NVDA down 3% on the news.
29
170
2,806
127,248
Jack O'Connor retweeted
An immigration court dropped its case against Turkish graduate student Rumeysa Ozturk, a little less than a year after federal agents arrested her on a street near Tufts University on.wsj.com/3Muu5ci
41
422
1,645
513,943
A lot of functional programmers think you can evaluate expressions lazily without changing the Big-O complexity of an algorithm. This is known as the "thunk cost fallacy" in Lisp, not to be confused with the "sunk cost fallacy" in lisp. x.com/drethelin/status/20191…

A lot of people think they can't afford to raise kids because they think every child needs their own bedroom. this is known as the bunk cost fallacy
6
220
Jack O'Connor retweeted
trivia: when the Super Heavy is firing at full thrust, it amounts on its own to about 1% of the total global human energy consumption
Not AI
49
51
1,363
117,643
Jack O'Connor retweeted
they dragged her away in chains and shipped her to Texas and only then checked, determined she was in fact here legally, and released her in Texas to figure out how to get back to Minnesota herself. and people wonder why her neighbors would protest!!!
"As her 13-year-old son wailed and her older daughter produced paperwork proving her mother was in the United States lawfully, the agents shackled Ms. Mehari and took her away." nytimes.com/2026/01/26/us/po…
196
11,063
52,495
1,365,495
The C strict aliasing rules are more complicated than you thought: "it is permitted to inspect the common initial part of [structs in a union] anywhere that ***a declaration of the completed type of the union is visible.***" (6.5.3.4 Structure and union members, paragraph 6)
1
3
129
Jack O'Connor retweeted
Announcing the Beta release of ty: an extremely fast type checker and language server for Python, written in Rust. We now use ty exclusively in our own projects and are ready to recommend it to motivated users. 10x, 50x, even 100x faster than existing type checkers and LSPs.
90
292
2,977
424,232
Jack O'Connor retweeted
A helpful post on polarization: Democratic voters shifted left in the 2010s, Republicans did not shift right. But in Congress it's the opposite. So each side can say the other one became extremists
Has the Democratic Party moved left? Yes, on some issues a lot (figure on the left). But the ideology of the Republican party has become far more extreme overall (figure on the right).
55
90
762
113,458
Accidental cancellation is one of the trickiest parts of async Rust, and some folks call it a design mistake. On the other hand in async Python, libraries like Trio create "nurseries" in part to make cancellation *more* automatic. Is this a "grass is greener" thing either way?
1
175
Jack O'Connor retweeted
Replying to @mmmBorck @HansFiene
4
4
84
6,512
Jack O'Connor retweeted
This week on Complex Systems I was joined by Will Wilson of Antithesis. The non-technical gloss is "We talked about how software breaks and is tested in the real world." The technical gloss: time-traveling debuggers in distributed systems.
5
7
75
14,367