Henry's notes on the JVM

Fan-in with Kotlin Coroutines and Flow
Sometimes you need to start several pieces of work at the same time and handle each result as soon as it is available. The fan-in pattern is a good fit for this: many concurrent producers send their r
Jul 22, 20266 min read
Accessing Apple's on-device AI from Kotlin using apfel
If you own a modern Mac with an Apple Silicon chip and Apple Intelligence enabled, then you already have access to a local foundation model. There is no separate model to download, no API key to creat
Jul 9, 20266 min read
H
Henry's notes on the JVM
4 posts
Practical notes on software development for the JVM, from Cape Town. Mostly Kotlin and Spring Boot: coroutines and structured concurrency, virtual threads, reactive programming, and the occasional Git trick or experiment with local AI models. Every post starts with something I actually needed to build, debug, or measure — so expect working code, real numbers, and honest trade-offs rather than theory. I also cover some of this on YouTube. All views are my own.
How many threads can you create with Spring Boot and Java virtual threads?
In looking at enabling virtual threads for a Spring Boot application, I began to wonder how many virtual threads I could spawn compared to platform threads. I knew the answer would be "many more", but
May 22, 20269 min read
Configure a background coroutine for your Spring Boot application
Sometimes you need to run work in the background of a Spring Boot application. This may be work that should not block the HTTP request that triggered it, or work that is started by a scheduled process
May 1, 20266 min read

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