Reddit Programming

Engineering a Columnar Database in Rust: Lessons on io_uring, SIMD, and why I avoided Async/Await
https://www.reddit.com/r/programming/comments/1qfkijn/engineering_a_columnar_database_in_rust_lessons/

I recently released the core engine for Frigatebird, an OLAP (Columnar) database built from scratch. While building it, I made a few architectural decisions that go against the "standard" Rust web/systems path. I wanted to share the rationale and the performance implications of those choices. 1. Why I ditched Async/Await for a Custom Runtime
The standard advice in Rust is "just use Tokio." However, generic async runtimes are designed primarily for IO-bound tasks with many idle connections. In a database execution pipeline, tasks are often CPU-heavy (scanning/filtering compressed pages). I found that mixing heavy compute with standard async executors led to unpredictable scheduling latency. Instead, I implemented a Morsel-Driven Parallelism model (inspired by DuckDB/Hyper): Queries are broken into "morsels" (fixed-size row groups). Instead of a central scheduler, worker threads use lock-free work stealing. A query job holds an AtomicUsize counter. Threads race to increment it (CAS), effectively "claiming" the next step of the pipeline. This keeps CPU cores pinned and maximizes instruction cache locality, as threads tend to stick to specific logic loops (Scanning vs Filtering). 2. Batched io_uring vs. Standard Syscalls
For the WAL (Write-Ahead Log), fsync latency is the killer. I built a custom storage engine ("Walrus") to leverage Linux's io_uring. Instead of issuing pwrite syscalls one by one, the writer constructs a submission queue of ~2,000 entries in userspace. It issues a single submit_and_wait syscall to flush them all. This reduced the context-switching overhead significantly, allowing the engine to saturate NVMe bandwidth on a single thread. 3. The "Spin-Lock" Allocator
This was the riskiest decision. Standard OS mutexes (pthread_mutex) put threads to sleep, costing microseconds. For the disk block allocator, I implemented a custom AtomicBool spin-lock. It spins in a tight loop (std::hint::spin_loop()) for nanoseconds. Trade-off: If the OS preempts the thread holding the lock, the system stalls. But because the critical section is just simple integer math (calculating offsets), it executes faster than the OS scheduler quantum, making this statistically safe and extremely fast. 4. Zero-Copy Serialization
I used rkyv instead of serde. Serde is great, but it usually involves deserialization steps (parsing bytes into structs). rkyv guarantees that the in-memory representation is identical to the on-disk representation, allowing for true zero-copy access by just casting pointers on the raw buffer. I'm curious if others here have hit similar walls with Tokio in CPU-bound contexts, or if I just failed to tune it correctly?  submitted by /u/Ok_Marionberry8922 (https://www.reddit.com/user/Ok_Marionberry8922)
[link] (https://github.com/Frigatebird-db/frigatebird) [comments] (https://www.reddit.com/r/programming/comments/1qfkijn/engineering_a_columnar_database_in_rust_lessons/)

3 views05:58

Reddit Programming

How to Build Decentralized Web Apps on Freenet Using Rust and WebAssembly
https://www.reddit.com/r/programming/comments/1qflgvq/how_to_build_decentralized_web_apps_on_freenet/

submitted by /u/sanity (https://www.reddit.com/user/sanity)
[link] (https://freenet.org/resources/manual/tutorial/) [comments] (https://www.reddit.com/r/programming/comments/1qflgvq/how_to_build_decentralized_web_apps_on_freenet/)

3 views05:59

Reddit Programming

Building A Provider-Agnostic Coding Agent
https://www.reddit.com/r/programming/comments/1qfnk7n/building_a_provideragnostic_coding_agent/

submitted by /u/Helpful_Geologist430 (https://www.reddit.com/user/Helpful_Geologist430)
[link] (https://cefboud.com/posts/provider-agnostic-coding-agent/) [comments] (https://www.reddit.com/r/programming/comments/1qfnk7n/building_a_provideragnostic_coding_agent/)

3 views06:00

Reddit Programming

- YouTube
https://www.reddit.com/r/programming/comments/1qfp3h9/youtube/

submitted by /u/ulyanovv (https://www.reddit.com/user/ulyanovv)
[link] (https://www.youtube.com/watch?v=-_RWkG8hloI) [comments] (https://www.reddit.com/r/programming/comments/1qfp3h9/youtube/)

3 views06:01

Reddit Programming

Tested a random APK with MobSF out of curiosity
https://www.reddit.com/r/programming/comments/1qg0i7h/tested_a_random_apk_with_mobsf_out_of_curiosity/

Hey everyone, Disclaimer: I'm a Flutter developer, not a security expert. This is purely a learning experiment from someone who got curious about mobile security tools. If I mess up terminology or miss something obvious, please correct me - that's literally why I'm posting this. I've been using an app APK for 2 years (which is not on the playstore). Got curious about mobile security tools, so I scanned it with MobSF. Setup (takes 2 minutes): docker run -it --rm -p 8000:8000 opensecurity/mobile-security-framework-mobsf Security Score: 44/100 Main findings: Debug Certificate - Signed with Android's default debug key. Anyone can modify and re-sign it. Cleartext Traffic Enabled - Been streaming over HTTP for 2 years. My ISP saw everything. Sketchy Permissions: GET_INSTALLED_APPLICATIONS - scanning what apps I have installed RECORD_AUDIO - no voice search exists in the app MobSF is ridiculously easy to use. If you've never scanned your own app, try it. For those who want more details, I wrote a step-by-step article with screenshots on Medium. You can find the link in my profile if you're interested. Not promoting anything - I'm not a Medium member so I don't earn from this. Just sharing for anyone who wants to learn more about the process.  submitted by /u/night-alien (https://www.reddit.com/user/night-alien)
[link] (https://medium.com/@web.pinkisingh/i-reverse-engineered-the-free-movie-app-i-used-for-2-years-the-results-were-terrifying-98796cef6837) [comments] (https://www.reddit.com/r/programming/comments/1qg0i7h/tested_a_random_apk_with_mobsf_out_of_curiosity/)

3 views09:17

Reddit Programming

MySQL’s popularity as ranked by DB-Engines started to tank hard, a trend that will likely accelerate in 2026.
https://www.reddit.com/r/programming/comments/1qg0p6p/mysqls_popularity_as_ranked_by_dbengines_started/

submitted by /u/thehashimwarren (https://www.reddit.com/user/thehashimwarren)
[link] (https://optimizedbyotto.com/post/reasons-to-stop-using-mysql/) [comments] (https://www.reddit.com/r/programming/comments/1qg0p6p/mysqls_popularity_as_ranked_by_dbengines_started/)

4 views09:18

Reddit Programming

Post-Quantum Panic: Transitioning Your Backend to NIST’s New Standards
https://www.reddit.com/r/programming/comments/1qg1pjj/postquantum_panic_transitioning_your_backend_to/

submitted by /u/JadeLuxe (https://www.reddit.com/user/JadeLuxe)
[link] (https://instatunnel.my/blog/post-quantum-panic-transitioning-your-backend-to-nists-new-standards) [comments] (https://www.reddit.com/r/programming/comments/1qg1pjj/postquantum_panic_transitioning_your_backend_to/)

4 views09:19

Reddit Programming

State of C 2026
https://www.reddit.com/r/programming/comments/1qg1tpd/state_of_c_2026/

submitted by /u/dev_newsletter (https://www.reddit.com/user/dev_newsletter)
[link] (https://devnewsletter.com/p/state-of-c-2026) [comments] (https://www.reddit.com/r/programming/comments/1qg1tpd/state_of_c_2026/)

4 views09:20

Reddit Programming

Democracy doesn't reward effort. It rewards memes. (From an experiment letting GitHub reactions decide what ships).
https://www.reddit.com/r/programming/comments/1qg5uv9/democracy_doesnt_reward_effort_it_rewards_memes/

submitted by /u/Equivalent-Yak2407 (https://www.reddit.com/user/Equivalent-Yak2407)
[link] (https://blog.openchaos.dev/posts/week-2-the-acceleration) [comments] (https://www.reddit.com/r/programming/comments/1qg5uv9/democracy_doesnt_reward_effort_it_rewards_memes/)

4 views07:15

Reddit Programming

The 7 deadly sins of software engineers productivity
https://www.reddit.com/r/programming/comments/1qg69su/the_7_deadly_sins_of_software_engineers/

submitted by /u/strategizeyourcareer (https://www.reddit.com/user/strategizeyourcareer)
[link] (https://strategizeyourcareer.com/p/the-7-deadly-sins-of-software-engineers-productivity) [comments] (https://www.reddit.com/r/programming/comments/1qg69su/the_7_deadly_sins_of_software_engineers/)

3 views07:16

Reddit Programming

A daily football crest guessing game (like Wordle but for crests)
https://www.reddit.com/r/programming/comments/1qg9ion/a_daily_football_crest_guessing_game_like_wordle/

Hey everyone! I've been teaching myself to code for the past few weeks and built this as my first proper project. How it works: You get a zoomed-in, blurred football crest and have 6 guesses to identify the club. Each wrong guess reveals a bit more of the crest. There's also a shirt color hint system to help you narrow it down. The game has: Daily Puzzle (same crest for everyone, resets at midnight) Practice Mode (unlimited random crests) Sprint Mode (10 crests, race against the clock) Still very much a work in progress and I'm sure there are bugs, but my mates have been enjoying it so thought I'd share here. Would love to hear what you think!  submitted by /u/olhaogabigol (https://www.reddit.com/user/olhaogabigol)
[link] (https://crestle-snowy.vercel.app/) [comments] (https://www.reddit.com/r/programming/comments/1qg9ion/a_daily_football_crest_guessing_game_like_wordle/)

2 views07:17

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