@cl4es

420 Followers
285 Following
36 Posts
OpenJDK dev @ Oracle, living just north of Stockholm, Sweden. He/him. 🏳️‍🌈👨‍👨‍👧
Bloghttps://cl4es.github.io
GitHubhttps://github.com/cl4es
cl4esOct 20
Wrote about performance improvments in the OpenJDK again: https://inside.java/2025/10/20/jdk-25-performance-improvements/
Performance Improvements in JDK 25 – Inside.java

Java is constantly evolving with ever increasing performance. JDK 25 comes with significant performance improvements compared to previous versions including scoped values, improved GCs, lots of compiler improvements, and much more.

cl4esFeb 23, 2023

Currently reading up on C1 code to see if it'd be easy enough to optimize array.clone() to be on par with new array + System.arraycopy

https://bugs.openjdk.org/browse/JDK-8302850

Might help with warmup - but also users who disable C2 for whatever reason. Also nice to tune out, focus and maybe learn a thing or two on the way...

[JDK-8302850] Consider implementing a C1 clone intrinsic that uses ArrayCopyNode for primitive arrays - Java Bug System

cl4esFeb 23, 2023
The bullshit concurrency level is too damned high!
cl4esFeb 22, 2023

"Unfortunately, you can't change the screen position of the Notification Center Alerts and Banners."

OK everyone please stop putting things in the upper right corner on your web pages then 🤷‍♂️

https://apple.stackexchange.com/questions/71989/change-location-of-macos-notification-center-alerts

Change location of macOS Notification Center alerts?

Is it possible to change where macOS Notification Center alerts appear on the screen? They currently appear at the top right of the screen with the menu bar: Alerts appearing in the top right ten...

Ask Different
cl4esFeb 20, 2023
Maybe it's time to build a new, better benchmarking harness.   https://xkcd.com/927/
Standards

xkcd
cl4esFeb 20, 2023
Another day, another uh.. 3 or 4 String-related optimizations...
cl4esFeb 14, 2023

We've been lining up some really nice performance improvements in the OpenJDK recently.

One of my favorites in the last few months is https://bugs.openjdk.org/browse/JDK-8297933 by Roland Westrelin (Red Hat). This has been seen to improve scores on entire benchmarks by double digits or even integer factors. Seems to be in a reasonably good state since 21 EA build 5.

[JDK-8297933] [REDO] Compiler should only use verified interface types for optimization - Java Bug System

cl4esFeb 14, 2023
Solar roof produced 35.6kWh today - even exported a few to the grid. Pretty decent for mid-February up here north of Stockholm.
cl4esFeb 14, 2023
Claes RedestadFeb 13, 2023
Had some fun leveraging vectorized mismatch to speed up a few java.lang.String methods... surprise 41x speed-ups were had: https://github.com/openjdk/jdk/pull/12528
8302163: Speed up various String comparison methods with ArraysSupport.mismatch by cl4es · Pull Request #12528 · openjdk/jdk

We can improve various String methods such as startsWith, endsWith and regionMatches by leveraging the intrinsified mismatch methods in ArraysSupport. Progress Change must be properly reviewed ...

GitHub
cl4esFeb 14, 2023
The small mastodon instance I picked at random is shutting down, so here I am picking a larger instance at random!