JDK 24 is out!! The final release before the new LTS coming in September.
https://blogs.oracle.com/java/post/the-arrival-of-java-24
https://blogs.oracle.com/java/post/the-arrival-of-java-24
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JDK 24 introduces the concept of an ahead-of-time cache which incrementally improves upon the CDS technology that has been a part of the JDK since 2004.
JEP 483 is a first deliverable of the Project Leyden whose goal it is to improve startup, warmup and footprint of Java programs while staying true to the dynamic nature of the Java language
https://inside.java/2025/03/19/performance-improvements-in-jdk24/
inside.java
Performance Improvements in JDK 24
Java is constantly evolving with ever increasing performance. JDK 24 comes with significant performance improvements compared to previous versions including improved virtual thread handling, reduced startup time, optimized FFM memory bulk operations…
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The kotlin-metadata-jvm library extracts structured information from compiled Kotlin .class files, such as class names, visibility, and signatures. You can use it in projects that need to analyze compiled Kotlin declarations.
https://kotlinlang.org/docs/metadata-jvm.html#modify-metadata
https://kotlinlang.org/docs/metadata-jvm.html#modify-metadata
Kotlin Help
Kotlin Metadata JVM library | Kotlin
Context parameters will replace context receivers, an evolution of the feature which addressed all provided feedback
More information on the migration from context receivers to context parameters and a reference to the new KEEP in the following post:
https://blog.jetbrains.com/kotlin/2025/04/update-on-context-parameters/
Context parameters are an upcoming feature in Kotlin, with a variety of use cases including more powerful extension methods and better tools for DSL development. Kotlin 2.2.0 will feature context parameters in Beta, and dedicated IntelliJ IDEA support will be available from 2025.1
More information on the migration from context receivers to context parameters and a reference to the new KEEP in the following post:
https://blog.jetbrains.com/kotlin/2025/04/update-on-context-parameters/
The JetBrains Blog
Update on Context Parameters - The JetBrains Blog
Context parameters will be replacing context receivers in Kotlin, with version 2.2.0 featuring them as Beta. We are committed to providing an easy migration between both features, including dedicated compiler and IntelliJ IDEA support.
Gradle 9 is approaching 🎉
https://docs.gradle.org/9.0.0-rc-3/userguide/upgrading_major_version_9.html
https://docs.gradle.org/9.0.0-rc-3/userguide/upgrading_major_version_9.html
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JVector, the library that powers DataStax Astra vector search, now supports indexing larger-than-memory datasets by performing construction-related searches with compressed vectors. This means that the edge lists need to fit in memory, but the uncompressed vectors do not, which gives us enough headroom to index Wikipedia-en on a laptop
https://foojay.io/today/indexing-all-of-wikipedia-on-a-laptop/
foojay
Indexing all of Wikipedia, on a laptop
foojay is the place for all OpenJDK Update Release Information. Learn More.
I will publish more detailed posts about most relevant features for me 🤞🤝
https://blogs.oracle.com/java/post/the-arrival-of-java-25
https://blogs.oracle.com/java/post/the-arrival-of-java-25
🚀 Java 25 introduces Compact Object Headers, a feature designed to shrink object sizes!
📦📏 This feature reduces the size of object headers from 96-128 bits down to just 64 bits on 64-bit systems.
🤔 What does this mean for your apps?
✅ Smaller heap sizes 💾
✅ Improved deployment density
✅ Increased data locality
This feature was included a experimental in Java 24 (JEP 450 - https://openjdk.org/jeps/450) 🧪 and is now a stable feature in Java 25 (JEP 519 - https://openjdk.org/jeps/519)! 🎉
⚠️ Important: It's not enabled by default. You need to activate it with a JVM flag.
💻 To enable it, simply use this command:
📚 Want to learn more? Check out the detailed article from InfoQ for performance benchmarks:
https://www.infoq.com/news/2025/06/java-25-compact-object-headers/
📦📏 This feature reduces the size of object headers from 96-128 bits down to just 64 bits on 64-bit systems.
🤔 What does this mean for your apps?
✅ Smaller heap sizes 💾
✅ Improved deployment density
✅ Increased data locality
This feature was included a experimental in Java 24 (JEP 450 - https://openjdk.org/jeps/450) 🧪 and is now a stable feature in Java 25 (JEP 519 - https://openjdk.org/jeps/519)! 🎉
⚠️ Important: It's not enabled by default. You need to activate it with a JVM flag.
💻 To enable it, simply use this command:
java -XX:+UseCompactObjectHeaders MyApp
📚 Want to learn more? Check out the detailed article from InfoQ for performance benchmarks:
https://www.infoq.com/news/2025/06/java-25-compact-object-headers/
InfoQ
Java 25 Integrates Compact Object Headers with JEP 519
Java 25 introduces Compact Object Headers (JEP 519), delivering up to 30% CPU savings and reduced memory usage for applications with small objects. This user-friendly feature compresses object headers from 12 bytes to 8, requiring only a JVM flag to activate.…
Ever call Java 21 an "LTS release"?
OpenJDK's own site already says it's "superseded." 💀
👉 https://jdk.java.net/21/
Friendly reminder:
LTS comes from vendors (Oracle, Azul, etc.), not OpenJDK.
OpenJDK just builds the JDK for ~6 months and dips. 😂
It's not an "LTS version," it's a version that gets LTS. Pass it on!
P.S. Yeah, this is a semantic debate, but it's relevant for understanding the difference between OpenJDK (the project), Java (the language), and the vendor distributions we all use. 👍
OpenJDK's own site already says it's "superseded." 💀
👉 https://jdk.java.net/21/
Friendly reminder:
LTS comes from vendors (Oracle, Azul, etc.), not OpenJDK.
OpenJDK just builds the JDK for ~6 months and dips. 😂
It's not an "LTS version," it's a version that gets LTS. Pass it on!
P.S. Yeah, this is a semantic debate, but it's relevant for understanding the difference between OpenJDK (the project), Java (the language), and the vendor distributions we all use. 👍
I have compiled a list of what I think are the most interesting and useful security enhancements in this release. I have also grouped them into appropriate categories (crypto, TLS, etc) which should make it easier to find out what has changed in each specific area
Summary
🔑 PEM Encodings: New API to easily handle keys/certs in PEM format.
⚙️ KDF API: Final version of API for deriving keys.
🛡️ SHA-1 Disabled: SHA-1 is now off by default for TLS handshakes.
✅ TLS/CNSA 1.0 Requirements: Adds modern algorithm requirements.
🚀 Performance: Faster crypto algorithms (ML-KEM, ML-DSA, ChaCha20).
https://seanjmullan.org/blog/2025/09/23/jdk25
Estaba viendo un video de la serie #RoadTo25 y encontré unas notas interesantes (https://cr.openjdk.org/~skuksenko/jep519/performance.txt) sobre las posibles regresiones de rendimiento al habilitar Compact Object Headers (COH).
El presentador habla de ello a partir del minuto 6:27 del video.
Obviamente, el resumen esta claro COH es un trade-off. En teoría, un menor consumo de memoria debería mejorar el rendimiento al reducir el use del recolector de basura (GC) y aprovechar mejor la caché de la CPU. Pero, como todo trade-off, tiene un coste, como tiempos de inicio más lentos o un impacto negativo en ciertos benchmarks.
Al parecer, construir un archivo de Class Data Sharing (CDS) puede ayudar a mitigar esos problemas de rendimiento en el arranque, no es una feature que yo haya usado y tengo la impresión que no es muy usada en general.
De todos modos, me encanta indagar en estas pequeñas peculiaridades porque me ayuda a entender mejor el potencial de la JVM como plataforma a gran escala.
📹 https://www.youtube.com/watch?v=renTMvh51iM&t=383s
El presentador habla de ello a partir del minuto 6:27 del video.
Obviamente, el resumen esta claro COH es un trade-off. En teoría, un menor consumo de memoria debería mejorar el rendimiento al reducir el use del recolector de basura (GC) y aprovechar mejor la caché de la CPU. Pero, como todo trade-off, tiene un coste, como tiempos de inicio más lentos o un impacto negativo en ciertos benchmarks.
Al parecer, construir un archivo de Class Data Sharing (CDS) puede ayudar a mitigar esos problemas de rendimiento en el arranque, no es una feature que yo haya usado y tengo la impresión que no es muy usada en general.
De todos modos, me encanta indagar en estas pequeñas peculiaridades porque me ayuda a entender mejor el potencial de la JVM como plataforma a gran escala.
📹 https://www.youtube.com/watch?v=renTMvh51iM&t=383s
YouTube
Java 21 ⮕ 25: Performance and Runtime Enhancements #RoadTo25
Every release of Java includes performance and runtime updates. For organizations moving from Java 21 to 25, that means a lot of release notes to review to understand all that has changed. Luckily Billy Korando from ACME Soft has already done all the work…
Ni me acordaba de los Applet ya 🤣
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Hasta Java 26 llegaron (https://openjdk.org/jeps/504), al parecer Firefox quitó soporte de applets en 2017
Si no sabes que era un applet 👉 https://www.vice.com/en/article/a-brief-history-of-the-java-applet/
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Remove the Applet API, which was deprecated for removal in JDK 17 (2021). It is obsolete because neither recent JDK releases nor current web browsers support applets.
Hasta Java 26 llegaron (https://openjdk.org/jeps/504), al parecer Firefox quitó soporte de applets en 2017
Si no sabes que era un applet 👉 https://www.vice.com/en/article/a-brief-history-of-the-java-applet/
VICE
The Rise and Fall of the Java Applet: Creative Coding’s Awkward Little Square
It's easy technology to hate, but the Applet predicted an age of web applications.