Alexander Reelsen
@spinscale.bsky.social
Husband, dad, enjoys working distributed, likes distributed databases & search engines, the JVM, Basketball/Streetball fan, gulps coffee, lives in Emsdetten/Germany, occasionally blogs at https://spinscale.de
Wanted to test the Junie CLI at the beginning of the year during the holidays as coding assisstant. Even with a Junie subscription I was waitlisted. So I tested opencode with a commercial model instead. Will hopefully have time to write all of this up at some point.
January 13, 2026 at 1:56 PM
Wanted to test the Junie CLI at the beginning of the year during the holidays as coding assisstant. Even with a Junie subscription I was waitlisted. So I tested opencode with a commercial model instead. Will hopefully have time to write all of this up at some point.
Reposted by Alexander Reelsen
"Building a good API is not trivial, and focus is required. The Elasticsearch Java SDK caught my attention because it actually gets this stuff right" — I'm pretty stoked to see my work being analyzed and recognized like this 😊 javapro.io/2026/01/13/e...
JAVAPRO International Elasticsearch Java SDK: No Magic, Just Solid Design Choices -
JAVAPRO International Elasticsearch Java SDK: No Magic, Just Solid Design Choices API & Frameworks - Open Source
javapro.io
January 13, 2026 at 10:32 AM
"Building a good API is not trivial, and focus is required. The Elasticsearch Java SDK caught my attention because it actually gets this stuff right" — I'm pretty stoked to see my work being analyzed and recognized like this 😊 javapro.io/2026/01/13/e...
frameworks for understanding databases
Nice introduction into the understanding tradeoffs that the thousands of database had to decide on, in order to deliver well on certain use-cases, but fail on others.
www.bitsxpages.com/p/frameworks...
Nice introduction into the understanding tradeoffs that the thousands of database had to decide on, in order to deliver well on certain use-cases, but fail on others.
www.bitsxpages.com/p/frameworks...
frameworks for understanding databases
building mental models for tradeoffs in performance, availability and durability in data systems
www.bitsxpages.com
January 12, 2026 at 1:56 PM
frameworks for understanding databases
Nice introduction into the understanding tradeoffs that the thousands of database had to decide on, in order to deliver well on certain use-cases, but fail on others.
www.bitsxpages.com/p/frameworks...
Nice introduction into the understanding tradeoffs that the thousands of database had to decide on, in order to deliver well on certain use-cases, but fail on others.
www.bitsxpages.com/p/frameworks...
dotstate - Manage your dotfiles with ease
Not just a CLI tool to manage dotfiles, but a full TUI. I'm still good with lnk at the moment I guess.
dotstate.serkan.dev
Not just a CLI tool to manage dotfiles, but a full TUI. I'm still good with lnk at the moment I guess.
dotstate.serkan.dev
DotState - Modern Dotfile Manager Built with Rust
Manage your dotfiles effortlessly. Sync to GitHub, GitLab, Bitbucket, or any git host. Organize by profiles and keep your configuration files safe. Built with Rust for speed and security.
dotstate.serkan.dev
January 11, 2026 at 2:35 PM
dotstate - Manage your dotfiles with ease
Not just a CLI tool to manage dotfiles, but a full TUI. I'm still good with lnk at the moment I guess.
dotstate.serkan.dev
Not just a CLI tool to manage dotfiles, but a full TUI. I'm still good with lnk at the moment I guess.
dotstate.serkan.dev
FossFLOW - Make beautiful isometric infrastructure diagrams
Browser based/react UI to create neat infrastructure diagrams.
Browser based/react UI to create neat infrastructure diagrams.
GitHub - stan-smith/FossFLOW: Make beautiful isometric infrastructure diagrams
Make beautiful isometric infrastructure diagrams. Contribute to stan-smith/FossFLOW development by creating an account on GitHub.
github.com
January 10, 2026 at 1:56 PM
FossFLOW - Make beautiful isometric infrastructure diagrams
Browser based/react UI to create neat infrastructure diagrams.
Browser based/react UI to create neat infrastructure diagrams.
bytechef - An open-source, AI-native, low-code platform for API orchestration, workflow automation, and AI agent integration
Looks like a JVM based n8n competitor under the Apache License.
Looks like a JVM based n8n competitor under the Apache License.
GitHub - bytechefhq/bytechef: Open-source, AI-native, low-code platform for API orchestration, workflow automation, and AI agent integration across internal systems and SaaS products.
Open-source, AI-native, low-code platform for API orchestration, workflow automation, and AI agent integration across internal systems and SaaS products. - bytechefhq/bytechef
github.com
January 9, 2026 at 1:56 PM
bytechef - An open-source, AI-native, low-code platform for API orchestration, workflow automation, and AI agent integration
Looks like a JVM based n8n competitor under the Apache License.
Looks like a JVM based n8n competitor under the Apache License.
Writing a good CLAUDE.md
Interesting summary: "It should define your project's WHY, WHAT, and HOW." This should happen regardless if machines or humans read your code.
Note to self: Test codex/claude code on personal projects in the next weeks.
www.humanlayer.dev/blog/writing...
Interesting summary: "It should define your project's WHY, WHAT, and HOW." This should happen regardless if machines or humans read your code.
Note to self: Test codex/claude code on personal projects in the next weeks.
www.humanlayer.dev/blog/writing...
Claude Code overview - Claude Code Docs
Learn about Claude Code, Anthropic's agentic coding tool that lives in your terminal and helps you turn ideas into code faster than ever before.
CLAUDE.md
January 8, 2026 at 1:56 PM
Writing a good CLAUDE.md
Interesting summary: "It should define your project's WHY, WHAT, and HOW." This should happen regardless if machines or humans read your code.
Note to self: Test codex/claude code on personal projects in the next weeks.
www.humanlayer.dev/blog/writing...
Interesting summary: "It should define your project's WHY, WHAT, and HOW." This should happen regardless if machines or humans read your code.
Note to self: Test codex/claude code on personal projects in the next weeks.
www.humanlayer.dev/blog/writing...
Building blobd: single-machine object store with sub-millisecond reads and 15 GB/s uploads
An experiment building a blob storage using Rust, async IO, io_uring, bypassing filesystems and page cache. Not meant to be production ready, but great read nontheless.
blog.wilsonl.in/blobd/
An experiment building a blob storage using Rust, async IO, io_uring, bypassing filesystems and page cache. Not meant to be production ready, but great read nontheless.
blog.wilsonl.in/blobd/
Building blobd: single-machine object store with sub-millisecond reads and 15 GB/s uploads
Deep dive into blobd, an object store designed for constant low latency reads using async Rust, io_uring and atomic writes
blog.wilsonl.in
January 7, 2026 at 1:56 PM
Building blobd: single-machine object store with sub-millisecond reads and 15 GB/s uploads
An experiment building a blob storage using Rust, async IO, io_uring, bypassing filesystems and page cache. Not meant to be production ready, but great read nontheless.
blog.wilsonl.in/blobd/
An experiment building a blob storage using Rust, async IO, io_uring, bypassing filesystems and page cache. Not meant to be production ready, but great read nontheless.
blog.wilsonl.in/blobd/
Sunboard - A privacy-first, local-only dashboard for your PV/solar data
A Javelit app, that can be configured via the browser, downloads data from the open AlphaESS API, visualizes power consumption, grid pushing and how much money you saved over the years.
github.com/spinscale/su...
A Javelit app, that can be configured via the browser, downloads data from the open AlphaESS API, visualizes power consumption, grid pushing and how much money you saved over the years.
github.com/spinscale/su...
January 6, 2026 at 1:56 PM
Sunboard - A privacy-first, local-only dashboard for your PV/solar data
A Javelit app, that can be configured via the browser, downloads data from the open AlphaESS API, visualizes power consumption, grid pushing and how much money you saved over the years.
github.com/spinscale/su...
A Javelit app, that can be configured via the browser, downloads data from the open AlphaESS API, visualizes power consumption, grid pushing and how much money you saved over the years.
github.com/spinscale/su...
Spinlocks vs. Mutexes: When to Spin and When to Sleep
Great introduction and explanation why sometimes wasting some CPU to spinlock is the better alternative to mutexes and sometimes it is vice versa, depending on contention.
howtech.substack.com/p/spinlocks-...
Great introduction and explanation why sometimes wasting some CPU to spinlock is the better alternative to mutexes and sometimes it is vice versa, depending on contention.
howtech.substack.com/p/spinlocks-...
Spinlocks vs. Mutexes: When to Spin and When to Sleep
You’re staring at perf top showing 60% CPU time in pthread_mutex_lock. Your latency is in the toilet. Someone suggests “just use a spinlock” and suddenly your 16-core server is pegged at 100% doing…
howtech.substack.com
January 5, 2026 at 1:56 PM
Spinlocks vs. Mutexes: When to Spin and When to Sleep
Great introduction and explanation why sometimes wasting some CPU to spinlock is the better alternative to mutexes and sometimes it is vice versa, depending on contention.
howtech.substack.com/p/spinlocks-...
Great introduction and explanation why sometimes wasting some CPU to spinlock is the better alternative to mutexes and sometimes it is vice versa, depending on contention.
howtech.substack.com/p/spinlocks-...
Concurrent Hash Table Designs: Synchronized, Sharding, ConcurrentHashMap, and NonBlockingHashMap
What a fantastic long read about different hash map implementations, speedups, trade-offs. Highly recommended sunday read.
bluuewhale.github.io/posts/concur...
What a fantastic long read about different hash map implementations, speedups, trade-offs. Highly recommended sunday read.
bluuewhale.github.io/posts/concur...
Concurrent Hash Table Designs: Synchronized, Sharding, ConcurrentHashMap, and NonBlockingHashMap
A tour of common concurrent hash map designs—global locks, sharding/lock striping, Java's ConcurrentHashMap, and Cliff Click's NonBlockingHashMap (NBHM)—through the lens of contention and performance.
bluuewhale.github.io
January 4, 2026 at 1:56 PM
Concurrent Hash Table Designs: Synchronized, Sharding, ConcurrentHashMap, and NonBlockingHashMap
What a fantastic long read about different hash map implementations, speedups, trade-offs. Highly recommended sunday read.
bluuewhale.github.io/posts/concur...
What a fantastic long read about different hash map implementations, speedups, trade-offs. Highly recommended sunday read.
bluuewhale.github.io/posts/concur...
Further Optimizing my Java SwissTable: Profile Pollution and SWAR Probing
second part of an awesome blog post improving performance via profiling and lots of prior knowledge that I do not have. Great read!
bluuewhale.github.io/posts/furthe...
second part of an awesome blog post improving performance via profiling and lots of prior knowledge that I do not have. Great read!
bluuewhale.github.io/posts/furthe...
Further Optimizing my Java SwissTable: Profile Pollution and SWAR Probing
A second round of Java SwissTable tuning: why Objects.equals polluted the profile, and why a SWAR probing loop beat the Vector API on ARM and x86.
bluuewhale.github.io
January 3, 2026 at 1:56 PM
Further Optimizing my Java SwissTable: Profile Pollution and SWAR Probing
second part of an awesome blog post improving performance via profiling and lots of prior knowledge that I do not have. Great read!
bluuewhale.github.io/posts/furthe...
second part of an awesome blog post improving performance via profiling and lots of prior knowledge that I do not have. Great read!
bluuewhale.github.io/posts/furthe...
Instant database clones with PostgreSQL 18
Nice approach of utilizing file system capabilities when cloning databases to prevent a full byte-per-byte copy. Which also implies this should only work within the same filesystem.
boringsql.com/posts/instan...
Nice approach of utilizing file system capabilities when cloning databases to prevent a full byte-per-byte copy. Which also implies this should only work within the same filesystem.
boringsql.com/posts/instan...
Instant database clones with PostgreSQL 18
Learn how to clone PostgreSQL databases instantly using reflinks. Turn slow template copies into milliseconds with PostgreSQL 18's new file copy options.
boringsql.com
January 2, 2026 at 1:56 PM
Instant database clones with PostgreSQL 18
Nice approach of utilizing file system capabilities when cloning databases to prevent a full byte-per-byte copy. Which also implies this should only work within the same filesystem.
boringsql.com/posts/instan...
Nice approach of utilizing file system capabilities when cloning databases to prevent a full byte-per-byte copy. Which also implies this should only work within the same filesystem.
boringsql.com/posts/instan...
sqlit - friendly TUI for SQL databases
written in python. supports quite a few databases, but tested with DuckDB only so far. Nice to quickly look something up.
github.com/Maxteabag/sq...
written in python. supports quite a few databases, but tested with DuckDB only so far. Nice to quickly look something up.
github.com/Maxteabag/sq...
GitHub - Maxteabag/sqlit: A user friendly TUI for SQL databases. Written in python. Supports SQL server, Mysql, PostreSQL and SQLite, Turso and more.
A user friendly TUI for SQL databases. Written in python. Supports SQL server, Mysql, PostreSQL and SQLite, Turso and more. - Maxteabag/sqlit
github.com
January 1, 2026 at 1:56 PM
sqlit - friendly TUI for SQL databases
written in python. supports quite a few databases, but tested with DuckDB only so far. Nice to quickly look something up.
github.com/Maxteabag/sq...
written in python. supports quite a few databases, but tested with DuckDB only so far. Nice to quickly look something up.
github.com/Maxteabag/sq...
Singularity - stealthy Linux Kernel Rootkit for modern kernels
So interesting to read about all the evasion techniques. Unfortunately there was a great blog post by kyntra that seems to have gone, that shows a lot of code samples how this works.
github.com/MatheuZSecur...
So interesting to read about all the evasion techniques. Unfortunately there was a great blog post by kyntra that seems to have gone, that shows a lot of code samples how this works.
github.com/MatheuZSecur...
GitHub - MatheuZSecurity/Singularity: Stealthy Linux Kernel Rootkit for modern kernels (6x)
Stealthy Linux Kernel Rootkit for modern kernels (6x) - MatheuZSecurity/Singularity
github.com
December 31, 2025 at 1:56 PM
Singularity - stealthy Linux Kernel Rootkit for modern kernels
So interesting to read about all the evasion techniques. Unfortunately there was a great blog post by kyntra that seems to have gone, that shows a lot of code samples how this works.
github.com/MatheuZSecur...
So interesting to read about all the evasion techniques. Unfortunately there was a great blog post by kyntra that seems to have gone, that shows a lot of code samples how this works.
github.com/MatheuZSecur...
kanata - improve keyboard comfort and usability with advanced customization
written in Rust, cross platform for all three platforms, however the configuration looks rather complex to me, so not sure I would use it. Especially since I am still a big Hammerspoon fan.
github.com/jtroo/kanata
written in Rust, cross platform for all three platforms, however the configuration looks rather complex to me, so not sure I would use it. Especially since I am still a big Hammerspoon fan.
github.com/jtroo/kanata
GitHub - jtroo/kanata: Improve keyboard comfort and usability with advanced customization
Improve keyboard comfort and usability with advanced customization - jtroo/kanata
github.com
December 30, 2025 at 1:56 PM
kanata - improve keyboard comfort and usability with advanced customization
written in Rust, cross platform for all three platforms, however the configuration looks rather complex to me, so not sure I would use it. Especially since I am still a big Hammerspoon fan.
github.com/jtroo/kanata
written in Rust, cross platform for all three platforms, however the configuration looks rather complex to me, so not sure I would use it. Especially since I am still a big Hammerspoon fan.
github.com/jtroo/kanata
snitch - a TUI ss / netstat for human
not to be confused with the osx firewalling tool named little snitch, this is just a small useful CLI tool.
github.com/karol-broda/...
not to be confused with the osx firewalling tool named little snitch, this is just a small useful CLI tool.
github.com/karol-broda/...
GitHub - karol-broda/snitch: a prettier way to inspect network connections
a prettier way to inspect network connections. Contribute to karol-broda/snitch development by creating an account on GitHub.
github.com
December 29, 2025 at 1:56 PM
snitch - a TUI ss / netstat for human
not to be confused with the osx firewalling tool named little snitch, this is just a small useful CLI tool.
github.com/karol-broda/...
not to be confused with the osx firewalling tool named little snitch, this is just a small useful CLI tool.
github.com/karol-broda/...
the last couple years in v8's garbage collector
nice summary and overview to read. It's always interesting to read how GC assumptions keep changing over the years, regardless of the underlying language.
wingolog.org/archives/202...
nice summary and overview to read. It's always interesting to read how GC assumptions keep changing over the years, regardless of the underlying language.
wingolog.org/archives/202...
the last couple years in v8's garbage collector — wingolog
wingolog: article: the last couple years in v8's garbage collector
wingolog.org
December 28, 2025 at 1:56 PM
the last couple years in v8's garbage collector
nice summary and overview to read. It's always interesting to read how GC assumptions keep changing over the years, regardless of the underlying language.
wingolog.org/archives/202...
nice summary and overview to read. It's always interesting to read how GC assumptions keep changing over the years, regardless of the underlying language.
wingolog.org/archives/202...
goalert - Open source on-call scheduling, automated escalations, and notifications
Maybe I missed it, but I didn't see an app, which probably would be the most important notification mechanism?
github.com/target/goalert
Maybe I missed it, but I didn't see an app, which probably would be the most important notification mechanism?
github.com/target/goalert
GitHub - target/goalert: Open source on-call scheduling, automated escalations, and notifications so you never miss a critical alert
Open source on-call scheduling, automated escalations, and notifications so you never miss a critical alert - target/goalert
github.com
December 27, 2025 at 1:56 PM
goalert - Open source on-call scheduling, automated escalations, and notifications
Maybe I missed it, but I didn't see an app, which probably would be the most important notification mechanism?
github.com/target/goalert
Maybe I missed it, but I didn't see an app, which probably would be the most important notification mechanism?
github.com/target/goalert
What Does a Database for SSDs Look Like?
Not only taking faster harddisks into account, but also networking, distributed logs and quite a bit more. It depends[tm]...
Not only taking faster harddisks into account, but also networking, distributed logs and quite a bit more. It depends[tm]...
What Does a Database for SSDs Look Like? - Marc's Blog
Maybe not what you think.
brooker.co.za
December 26, 2025 at 1:56 PM
What Does a Database for SSDs Look Like?
Not only taking faster harddisks into account, but also networking, distributed logs and quite a bit more. It depends[tm]...
Not only taking faster harddisks into account, but also networking, distributed logs and quite a bit more. It depends[tm]...
Full Unicode Search at 50× ICU Speed with AVX‑512
Long read about all the StringZilla optimizations to speed up unicode search. First example shown is of course German :-)
Long read about all the StringZilla optimizations to speed up unicode search. First example shown is of course German :-)
Full Unicode Search at 50× ICU Speed with AVX‑512
ICU gets Unicode right and pays for it. This post shows a different approach: fold-safe windows, SIMD probes, and verifiers for fast UTF‑8 search.
ashvardanian.com
December 25, 2025 at 1:56 PM
Full Unicode Search at 50× ICU Speed with AVX‑512
Long read about all the StringZilla optimizations to speed up unicode search. First example shown is of course German :-)
Long read about all the StringZilla optimizations to speed up unicode search. First example shown is of course German :-)
hash-smith: Fast & memory efficient hash tables for Java
The description also contains a longer blog post about porting SwissTable to Java after Rust and Go went with it as defaults.
github.com/bluuewhale/h...
The description also contains a longer blog post about porting SwissTable to Java after Rust and Go went with it as defaults.
github.com/bluuewhale/h...
GitHub - bluuewhale/hash-smith: Fast & memory efficient hash tables for Java
Fast & memory efficient hash tables for Java. Contribute to bluuewhale/hash-smith development by creating an account on GitHub.
github.com
December 23, 2025 at 1:56 PM
hash-smith: Fast & memory efficient hash tables for Java
The description also contains a longer blog post about porting SwissTable to Java after Rust and Go went with it as defaults.
github.com/bluuewhale/h...
The description also contains a longer blog post about porting SwissTable to Java after Rust and Go went with it as defaults.
github.com/bluuewhale/h...
Biscuit - a specialized PostgreSQL index access method designed fast matching on LIKE queries
Uses roaring bitmaps, only works on LIKE queries, but not with regexes or collations, index needs to be in memory.
Uses roaring bitmaps, only works on LIKE queries, but not with regexes or collations, index needs to be in memory.
GitHub - CrystallineCore/Biscuit: Biscuit is a specialized PostgreSQL index access method (IAM) designed for blazing-fast pattern matching on LIKE queries, with native support for multi-column searches. It eliminates the recheck overhead of trigram indexes while delivering significant performance improvements on wildcard-heavy queries.
Biscuit is a specialized PostgreSQL index access method (IAM) designed for blazing-fast pattern matching on LIKE queries, with native support for multi-column searches. It eliminates the recheck ov...
github.com
December 22, 2025 at 1:56 PM
Biscuit - a specialized PostgreSQL index access method designed fast matching on LIKE queries
Uses roaring bitmaps, only works on LIKE queries, but not with regexes or collations, index needs to be in memory.
Uses roaring bitmaps, only works on LIKE queries, but not with regexes or collations, index needs to be in memory.
waterfox - A privacy-focused, performance-oriented browser based on Firefox
Guess the recent announcements from Mozilla will bring a bunch of users to a fleet of forks.
www.waterfox.com
Guess the recent announcements from Mozilla will bring a bunch of users to a fleet of forks.
www.waterfox.com
Waterfox - Open source web browser
The web browser that respects your privacy
www.waterfox.com
December 21, 2025 at 1:56 PM
waterfox - A privacy-focused, performance-oriented browser based on Firefox
Guess the recent announcements from Mozilla will bring a bunch of users to a fleet of forks.
www.waterfox.com
Guess the recent announcements from Mozilla will bring a bunch of users to a fleet of forks.
www.waterfox.com
If you have not yet enough of all the tech advent calendars, take a look at the Elastic one. this year, as it contains quite a few small and useful snippets all across the stack and I am sure you will learn a thing or two.
Check it out at
Check it out at
Advent Calendar
To celebrate the end of the calendar year, the Elastic Engineering team will be publishing a series of Elastic Stack tips each day, from the 1st of December through the 25th of December. As we are a…
discuss.elastic.co
December 20, 2025 at 1:56 PM
If you have not yet enough of all the tech advent calendars, take a look at the Elastic one. this year, as it contains quite a few small and useful snippets all across the stack and I am sure you will learn a thing or two.
Check it out at
Check it out at