frontpage.
newsnewestaskshowjobs

Open Source @Github

fp.

Open in hackernews

The Scalar Select Anti-Pattern

https://matklad.github.io/2025/05/14/scalar-select-aniti-pattern.html
47•goranmoomin•1y ago

Comments

castratikron•1y ago
As long as processing one event does not affect any of the other events in the batch. E.g. events are file IO, and processing one event causes another event's descriptor to get closed before that event can be processed.
wahern•1y ago
If the close routine on an event source, or the low-level (e.g. epoll) registration, deregistration, and dequeueing logic doesn't know how to keep polling and liveness state consistent between userspace and the kernel, they've got much bigger problems. This looks like Rust code so I would hope the event stream libraries are, e.g., keeping Rc'd file objects and properly managing reference integrity viz-a-viz kernel state before the application caller ever sees the first dequeued event in a cycle. This is a perennial issue with event loop libraries and buggy application code (in every language). One can't just deal with raw file descriptors, call the close syscall directly, etc, hoping to keep state consistent implicitly. There's an unavoidable tie-in needed between application's wrappers around low-level resources and the event loop in use.
taeric•1y ago
I'm not entirely clear on what the proposal is at the end? Seems that the long term answer as to "which of these implications to pursue" is "all of them?" Simply taking in a batch of instructions doesn't immediately change much? You still have to be able to do each of the other things. And you will still expect some dependencies between batches that could possibly interact in the same ways.

In a sense, this is no different than how your processor is dealing with instructions coming in. You will have some instructions that can be run without waiting on previous ones. You will have some that can complete quickly. You will have some that are stalled on other parts of the system. (I'm sure I could keep wording an instruction to match each of the implications.)

To that end, part of your program has to deal with taking off "whats next" and finding how to prepare that to pass to the execution portion of your program. You can make that only take in batches, but you are almost certainly responsible for how you chunk them moreso than whatever process is sending the instructions to you? Even if you are handed clear batches, it is incumbent on you to batch them as they go off to the rest of the system.

lmz•1y ago
I guess the proposal is "instead of fetching and acting on one event at a time, consider fetching all available events and look for opportunities to optimize which ones you process (e.g. by prioritization or by skipping certain events if superseded by newer ones)".
taeric•1y ago
I mean, I got that. But you could as easily say "instead of fetching and acting on one event at a time, fetch and triage/route instructions into applicable queues."

In particular, there is no guarantee that moving to batches changes any of the problems you may have from acting on a single one at a time. To that end, you will have to look into all of the other strategies sooner or later.

Following from that, the problem is not "processMessage" or whatever. The problem is that you haven't broken "processMessage" up into the constituent "receive/triage/process/resolve" loop that you almost certainly will have to end up with.

malkia•1y ago
in CPU's - pipelining!
jchw•1y ago
I believe something similar is going on internally in Windows with event queues. It coalesces and prioritizes input events when multiple of them pile up before you're able to pop new events off of the queue. (For some events, e.g. pointer events, you can even go and query frames that were coalesced during input handling.) On the application/API end, it just looks like a "scalar select" loop, but actually it is doing batching behavior for input events!

(On the flip side, if you have a Wayland client that falls behind on processing its event queue, it can crash. On the whole this isn't really that bad but if you have something sending a shit load of events it can cause very bad behavior. This has made me wonder if it's possible, with UNIX domain sockets, to implement some kind of event coalescing on the server-side, to avoid flooding the client with high-precision pointer movement events while it's falling behind. Maybe start coalescing when FIONREAD gets to some high watermark? No idea...)

Show HN: Wikihack – HackerTube, but for Wikipedia articles mentioned on HN

https://wikihack.netlify.app
55•aizk•2h ago•14 comments

Show HN: HackerBooks – HackerTube, but for books mentioned on HN

https://hackerbooks.org
1270•roansh•15h ago•223 comments

Postgres 19 is late because so many more bugs are being found now

http://rhaas.blogspot.com/2026/10/postgres-19-is-late-and-its-ais-fault.html
315•soheilpro•2d ago•205 comments

F/OSS Comics #13: BSD Unix, Part 3 – The Beginning of BSD Unix

https://fosscomics.com/posts/13.%20BSD%20Unix%20Part%203%20-%20The%20Beginning%20of%20BSD%20Unix/
89•joonehur•5h ago•8 comments

HackerTube: YouTube built from videos recommended by HN

https://karpathy.bearblog.dev/hacker-tube/
2488•karpathy•1d ago•556 comments

Ask HN: Which TV do you recommend for privacy?

298•LecroJS•12h ago•454 comments

Mystery of 60-Second Fluctuations in Power Grids Solved

https://www.fz-juelich.de/en/news/archive/press-release/2026/mystery-of-60-second-fluctuations-in...
95•_Microft•1d ago•40 comments

Trigger.dev customer environment variables exposed

https://trigger.dev/blog/security-incident-nov-2026
67•anurag•6h ago•26 comments

Bones may release proteins that slow aging and extend life span

https://www.science.org/content/article/bones-may-release-proteins-slow-aging-and-extend-life-span
37•EA-3167•6h ago•3 comments

Nibnib: Image compression with extreme decompression speed

https://github.com/raphlinus/nibnib
130•raphlinus•3d ago•22 comments

Tips for more effective fuzz testing with AFL++

https://nullprogram.com/blog/2025/02/05/
110•luu•4d ago•17 comments

Copper – A minimal low-level programming language with OOP and generics

https://tibleiz.net/copper/
156•bogdanoff_2•2d ago•89 comments

Show HN: OmniDiff – Opensource, super fast, content aware Git difftool, in Rust

https://github.com/ivankovic/omnidiff
218•FabCH•18h ago•52 comments

New 3D thermal invisibility cloak makes objects disappear from infrared cameras

https://www.sciencedaily.com/releases/2026/10/261025073051.htm
72•stevenalowe•3d ago•33 comments

Proving and improving the Platonic Representation Hypothesis with JEPAs

https://arxiv.org/abs/2610.39302
132•Anon84•18h ago•67 comments

The AI cost of JavaScript frameworks

https://nolanlawson.com/2026/10/28/the-ai-cost-of-javascript-frameworks/
352•luu•1d ago•273 comments

One-minute frequency disturbances from synchronization in power systems

https://www.nature.com/articles/s41560-026-02144-0
146•croes•1d ago•49 comments

Mathematics has changed. Let's act like it

https://terrytao.wordpress.com/2026/11/01/mathematics-has-changed-lets-act-like-it/
286•smilelamp•13h ago•302 comments

Show HN: Point your camera at a landscape to learn about its geology

https://outcrop.rocks/
191•headsupernova•3d ago•41 comments

Lenovo's 'encrypted' fingerprint USB is just an unencrypted SD card in a case

https://www.reddit.com/r/technology/comments/1xl2pr3/lenovos_encrypted_fingerprint_usb_drive_is_j...
461•entryleveljobsc•17h ago•157 comments

Bidirectional charging during grid outages

https://www.jefftk.com/p/bidirectional-charging-during-grid-outages
98•luu•1d ago•145 comments

Radiation Map of the World

https://radiaverse.com/
158•slater•4d ago•47 comments

OccupySaaS

https://occupysaas.com/
206•misswaterfairy•7h ago•135 comments

Show HN: I rebuilt my old canvas 3D library as a small WebGL 2 library – phoria2

https://kevs3d.co.uk/phoria2/
87•kevs3d•1d ago•17 comments

Keeping Up Appearances – The women taking over the funeral industry

https://lareviewofbooks.org/article/death-industry-mortuary-programs-women-andie-eisen-quarterly/
42•TMWNN•2d ago•21 comments

I Am the Reason OpenAI Is Killing Unlimited Chats

https://chaosmanage.github.io/i-killed-unlimited-chatgpt/
49•gulmothrowaway•14h ago•12 comments

Domain hacks with unusual Unicode characters (2018)

https://shkspr.mobi/blog/2018/11/domain-hacks-with-unusual-unicode-characters/
73•n_plus_1_acc•20h ago•51 comments

Seoul Viosys begins production of rare-earth-free white light emitter

https://www.semiconductor-today.com/news_items/2026/oct/seoul-291026.shtml
166•gmays•15h ago•48 comments

An Italian farmer found some unknown seeds in his attic and planted them

https://www.smithsonianmag.com/science-nature/italian-farmer-found-unknown-seeds-attic-with-nothi...
795•ecares•1d ago•203 comments

AI fan wikis riddled with errors are muddying the waters of games culture

https://www.eurogamer.net/ai-fan-wikis-errors-complicating-games-culture
78•rdmuser•5h ago•64 comments