Erik Österlund
@eosterlund.bsky.social
OpenJDK HotSpot JVM developer at Oracle. Drinks coffee and pets cats. Opinions expressed are, unsurprisingly, my own.
Reposted by Erik Österlund
#Java peers, #JavaOne 2026 is right around the corner! Read my LinkedIn article to learn more about the conference's value...and of course, register now!
www.linkedin.com/pulse/javaon...
www.linkedin.com/pulse/javaon...
JavaOne...30 Years of Java and the Community That Keeps It Moving
Register Now for JavaOne 2026 | March 17-19 | Redwood City, California For three decades, Java has been a constant in an industry defined by change. Frameworks come and go, architectures shift, and ha...
www.linkedin.com
January 30, 2026 at 2:38 PM
#Java peers, #JavaOne 2026 is right around the corner! Read my LinkedIn article to learn more about the conference's value...and of course, register now!
www.linkedin.com/pulse/javaon...
www.linkedin.com/pulse/javaon...
That’s pretty cool. This reminds me I live somewhere with very limited light pollution. Perhaps I should have a go.
January 17, 2026 at 10:01 AM
That’s pretty cool. This reminds me I live somewhere with very limited light pollution. Perhaps I should have a go.
After working on ZGC for a decade, I’m happy to announce that I’m publishing a book about ZGC in JDK 25. It ships 22 May (www.taylorfrancis.com/books/mono/1...) and is being published by Taylor & Francis. You should get a copy if you want to learn more about ZGC. It’s available for pre-order now.
The Z Garbage Collector | In JDK 25 | Erik Österlund | Taylor & Franci
This book explains how the Z Garbage Collector was designed, why it was designed this way, the common pitfalls to avoid when using ZGC in JDK 25 and how to get
https://www.taylorfrancis.com/books/mono/10.1201/9781003595366/garbage-collector-erik-österlund
January 15, 2026 at 4:57 PM
After working on ZGC for a decade, I’m happy to announce that I’m publishing a book about ZGC in JDK 25. It ships 22 May (www.taylorfrancis.com/books/mono/1...) and is being published by Taylor & Francis. You should get a copy if you want to learn more about ZGC. It’s available for pre-order now.
Reposted by Erik Österlund
📢Important Update 📢
Many have asked for more time to submit to the 2026 #JavaOne call for papers. We've extended the deadline until Nov 13th at 11:59pm PT. Be sure to submit your #Java proposal(s) before time runs out:
➡️ social.ora.cl/6013A7UXF
Many have asked for more time to submit to the 2026 #JavaOne call for papers. We've extended the deadline until Nov 13th at 11:59pm PT. Be sure to submit your #Java proposal(s) before time runs out:
➡️ social.ora.cl/6013A7UXF
November 11, 2025 at 5:43 PM
📢Important Update 📢
Many have asked for more time to submit to the 2026 #JavaOne call for papers. We've extended the deadline until Nov 13th at 11:59pm PT. Be sure to submit your #Java proposal(s) before time runs out:
➡️ social.ora.cl/6013A7UXF
Many have asked for more time to submit to the 2026 #JavaOne call for papers. We've extended the deadline until Nov 13th at 11:59pm PT. Be sure to submit your #Java proposal(s) before time runs out:
➡️ social.ora.cl/6013A7UXF
Integrated ”JEP 516: Ahead-of-Time Object Caching with Any GC”!
openjdk.org/jeps/516
openjdk.org/jeps/516
openjdk.org
November 7, 2025 at 6:12 PM
Integrated ”JEP 516: Ahead-of-Time Object Caching with Any GC”!
openjdk.org/jeps/516
openjdk.org/jeps/516
This is an awesome oak tree close to where I live.
October 12, 2025 at 10:50 AM
This is an awesome oak tree close to where I live.
That is a good oak.
Another photo of the Arbour Oak in Wollaton Park, Nottingham
Courtesy of my son Elliott, who was enjoying University Freshers Week by getting to know the local oak legends, & not just the pubs
Courtesy of my son Elliott, who was enjoying University Freshers Week by getting to know the local oak legends, & not just the pubs
October 5, 2025 at 8:25 AM
That is a good oak.
Glad you enjoyed it. 🙂
July 14, 2025 at 6:12 PM
Glad you enjoyed it. 🙂
Reposted by Erik Österlund
JDK 25 has been branched from the main line and is now in Rampdown Phase One: mail.openjdk.org/pipermail/jd...
openjdk.org/projects/jdk...
#JDK25 #OpenJDK #Java
openjdk.org/projects/jdk...
#JDK25 #OpenJDK #Java
JDK 25 is now in Rampdown Phase One
mail.openjdk.org
June 5, 2025 at 5:24 PM
JDK 25 has been branched from the main line and is now in Rampdown Phase One: mail.openjdk.org/pipermail/jd...
openjdk.org/projects/jdk...
#JDK25 #OpenJDK #Java
openjdk.org/projects/jdk...
#JDK25 #OpenJDK #Java
It’s 5 days left to JavaOne. Go buy a ticket if you haven’t already! And don’t miss my session about what we are cooking in the ZGC project right now: reg.rf.oracle.com/flow/oracle/...
Session Catalog
reg.rf.oracle.com
March 13, 2025 at 5:47 PM
It’s 5 days left to JavaOne. Go buy a ticket if you haven’t already! And don’t miss my session about what we are cooking in the ZGC project right now: reg.rf.oracle.com/flow/oracle/...
Reposted by Erik Österlund
#Java developers!
@JavaOne is BACK (18-20 Mar). Early bird registration is available through Feb 9th. Please (re)join us at THE conference that started it all...
Blog ➡️ social.ora.cl/6015Qne5z
Event ➡️ javaone.com
#JavaOne #OpenJDK #JDK
@JavaOne is BACK (18-20 Mar). Early bird registration is available through Feb 9th. Please (re)join us at THE conference that started it all...
Blog ➡️ social.ora.cl/6015Qne5z
Event ➡️ javaone.com
#JavaOne #OpenJDK #JDK
December 23, 2024 at 5:46 PM
#Java developers!
@JavaOne is BACK (18-20 Mar). Early bird registration is available through Feb 9th. Please (re)join us at THE conference that started it all...
Blog ➡️ social.ora.cl/6015Qne5z
Event ➡️ javaone.com
#JavaOne #OpenJDK #JDK
@JavaOne is BACK (18-20 Mar). Early bird registration is available through Feb 9th. Please (re)join us at THE conference that started it all...
Blog ➡️ social.ora.cl/6015Qne5z
Event ➡️ javaone.com
#JavaOne #OpenJDK #JDK
You missed one use case: entertaining GC developers. We can deduplicate String payload. We *could* canonicalize the String identity as well, but that might accidentally make broken code using == work. And it’s so much more hilarious to eagerly wait for the == to run and inevitably bug out!
elmo from sesame street is on fire with his arms outstretched and the words `` let it burn '' .
ALT: elmo from sesame street is on fire with his arms outstretched and the words `` let it burn '' .
media.tenor.com
December 18, 2024 at 8:02 AM
You missed one use case: entertaining GC developers. We can deduplicate String payload. We *could* canonicalize the String identity as well, but that might accidentally make broken code using == work. And it’s so much more hilarious to eagerly wait for the == to run and inevitably bug out!
I used to have a bunch of followers on here. Now I can’t find them any more; it just says 404.
December 6, 2024 at 10:31 AM
I used to have a bunch of followers on here. Now I can’t find them any more; it just says 404.
Reposted by Erik Österlund
Looks like Cassandra is getting support for JDK 21 and decided to switch GC to Generational ZGC. Good choice! I like how GC pause warning threshold changed from 1 second to 10 ms and logging threshold from 200 ms to 2 ms. PR: github.com/apache/cassa...
Add JDK21 support by jmckenzie-dev · Pull Request #3696 · apache/cassandra
Add JDK21 support
Patch by jmckenzie; reviewed by TBD for CASSANDRA-18831
github.com
November 29, 2024 at 8:27 PM
Looks like Cassandra is getting support for JDK 21 and decided to switch GC to Generational ZGC. Good choice! I like how GC pause warning threshold changed from 1 second to 10 ms and logging threshold from 200 ms to 2 ms. PR: github.com/apache/cassa...
I finally deactivated my ”X” account after a long time of not using it. I simply don’t want to go back there.
November 24, 2024 at 10:32 AM
I finally deactivated my ”X” account after a long time of not using it. I simply don’t want to go back there.
Ah so you are approaching this like instrumentation based profiling? I thought you would be the statistical sampling kind of guy.
November 21, 2024 at 6:27 PM
Ah so you are approaching this like instrumentation based profiling? I thought you would be the statistical sampling kind of guy.
Sure. What you do is to go to a place full of garbage, evacuate the stuff you care about to a safe place, then nuke the entire place.
November 15, 2024 at 8:33 AM
Sure. What you do is to go to a place full of garbage, evacuate the stuff you care about to a safe place, then nuke the entire place.
I migrated to bluesky rather early. Why? Because I know garbage when I see it.
November 15, 2024 at 8:13 AM
I migrated to bluesky rather early. Why? Because I know garbage when I see it.
We don’t really plan for things to ship at a particular release. We will see how things pan out.
November 15, 2024 at 6:30 AM
We don’t really plan for things to ship at a particular release. We will see how things pan out.
Reposted by Erik Österlund
Helidon 4.1.4 is out now!
This release contains important bugfixes and enhancements and is recommended for all users of Helidon 4.
github.com/helidon-io/h...
This release contains important bugfixes and enhancements and is recommended for all users of Helidon 4.
github.com/helidon-io/h...
November 14, 2024 at 10:41 AM
Helidon 4.1.4 is out now!
This release contains important bugfixes and enhancements and is recommended for all users of Helidon 4.
github.com/helidon-io/h...
This release contains important bugfixes and enhancements and is recommended for all users of Helidon 4.
github.com/helidon-io/h...
My work on ZGC automatic heap sizing is coming together beautifully. I’m increasingly happy with the GC logs. Feeling optimistic that it can beat carefully tuned manual heap sizing. A static heap size just can’t deal with dynamic behaviour shifts as well; it’s not in its nature.
November 14, 2024 at 8:16 PM
My work on ZGC automatic heap sizing is coming together beautifully. I’m increasingly happy with the GC logs. Feeling optimistic that it can beat carefully tuned manual heap sizing. A static heap size just can’t deal with dynamic behaviour shifts as well; it’s not in its nature.
Reposted by Erik Österlund
Twitter was a good ride. Hard to leave 65K followers behind, but hard to stay there too. Let's try things where the sky is blue!
November 14, 2024 at 12:20 AM
Twitter was a good ride. Hard to leave 65K followers behind, but hard to stay there too. Let's try things where the sky is blue!
So if I want memory safety in an app, would I be ”just wrong” for thinking it’s easier to get that from a GC compared to a borrow checker?
November 13, 2024 at 10:05 PM
So if I want memory safety in an app, would I be ”just wrong” for thinking it’s easier to get that from a GC compared to a borrow checker?
I don’t know. When I talk to people writing rust for systems programming, they say its lack of ABI and dynamic linking friction makes it a poor choice, but pretty sure it’s good for apps. And the people writing apps say while it’s hard to get things wrong it’s too hard to get anything right.
November 13, 2024 at 7:37 PM
I don’t know. When I talk to people writing rust for systems programming, they say its lack of ABI and dynamic linking friction makes it a poor choice, but pretty sure it’s good for apps. And the people writing apps say while it’s hard to get things wrong it’s too hard to get anything right.