Project Valhalla
Java language feature in Developer tools
Brings value types to Java, removing the performance cost of small objects; people welcome the long-awaited change. Critics say it is slow, adds complexity, and may give smaller performance gains than hoped.
14 people recommended Project Valhalla in Hacker News comments, 2 had mixed feelings and 13 criticized it, November 2025 to October 2026.
Summary written by Claude from 36 comments.
29 people gave an opinion
- recommend it
- 14
- mixed feelings
- 2
- warn against or regret it
- 13
The record
Recommended in 8 of 12 months
In 12 different threads.
- November 2025: recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: not recommended
- March 2026: recommended
- April 2026: not recommended
- May 2026: recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: not recommended
Why it doesn’t carry the badge
- 14 people recommend itNeeds 10 or more, met.
- 1 recommender for every criticNeeds 2 to 1 or better, not met.
- Recommended in 8 of 12 monthsNeeds 4 or more, met.
- Recommended in 12 threadsNeeds 5 or more, met.
- The biggest thread supplies 36% of its recommendersNeeds half or less, met.
The same rules apply to every product, and the badge can’t be bought. Mixed feelings count toward neither side. How the badge works
What people say about it
Reasons grouped from a sample of 36 of the 37 opinions about it, picked in proportion to how many people recommend it, have mixed feelings and criticize it. Each mark is one comment in the sample. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Long-awaited change finally arriving
“can't wait for Project Valhalla, going into preview shortly”
Comment from 13 Jul 2026 in “Tune Code Before Your Garbage Collector” “it's nice to see Valhalla finally beocming reality”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “But Valhalla has been a veeery long time coming.”
Comment from 17 Mar 2026 in “Java 26 is here, and with it a solid foundation for the future” - Comment from 11 Jul 2026 in “Your code is fast – if you're lucky”
Thoughtful semantics and design
“It transcends the binary understanding of object vs value and actually defines 4 distinct buckets”
Comment from 31 Jul 2026 in “JEP 401: Value Objects (Preview) merged to OpenJDK master” “a beautiful specification that put semantics and performance payoff first and syntax seconds”
Comment from 31 Jul 2026 in “JEP 401: Value Objects (Preview) merged to OpenJDK master” “Valhalla brings features that address key problems, and they didn’t rush to it either.”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” - Comment from 20 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28”
Major step for Java value types
“with Valhalla design now being merged into the language (Java 28+) we get explicit value types”
Comment from 14 Aug 2026 in “What Garbage Collection Costs” “Project Valhalla will be the most significant change to the JVM in a very long time”
Comment from 17 Mar 2026 in “Java 26 is here, and with it a solid foundation for the future” “First step to an interesting direction of the language.”
Comment from 10 Jun 2026 in “First Valhalla related stuff will land in Java 28” Removes performance cost of small objects
“they are really late to the party with this but it's good. The performance boost will be welcome”
Comment from 20 May 2026 in “Java: Rethink Domain Primitives with Valhalla” “Valhalla removes the historical performance tax on tiny domain objects.”
Comment from 19 May 2026 in “Java: Rethink Domain Primitives with Valhalla”
What people warn about
Each mark is one comment
Slow, bureaucratic, not yet mainstream
“This beaurcratic development feels like turning a super-tanker that's connected to a hundred other super-tankers.”
Comment from 20 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “Afaik Project Valhalla still hasn't become mainstream even after almost _12_ years at this point”
Comment from 10 Apr 2026 in “Principles of Mechanical Sympathy” “It's currently locked up by project Valhalla which is a bit of a meme.”
Comment from 7 Oct 2026 in “Mastering SIMD with Java Vector API” - Comment from 15 Sep 2026 in “Java 27”
Performance gains may be limited
“At what cost? A key benefit of value types is improved performance but AFAIK Valhalla doesn't even let you pass them by reference.”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “to me this suggests that the performance gains from Project Valhalla in this Java will be minimal.”
Comment from 27 Aug 2026 in “Value Classes Still Need Compiler Sympathy” “this is anyway an extremely limited perf enhancement”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” Wrong approach, unlikely to be default
“I think this alone shows this project can’t ever be turned on by default”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “Which is why this is the wrong approach. Again. This is a major misstep.”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “I fail to see the point of this entire project”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” Null safety and thread-safety concerns
“So, this basically makes every value-object optional, adds extra overhead and makes code less safe to null pointer dereference errors.”
Comment from 20 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28” “It will make it really hard to extract a lot of the benefit of valhala if you can't make a thread unsafe value class.”
Comment from 19 Jun 2026 in “Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28”
What people said
36 of the 37 opinions about it, picked in proportion to the three counts, newest first. Each links to the original comment.
“It's currently locked up by project Valhalla which is a bit of a meme.”
“it made project Valhalla possible”
“They were too slow with Valhalla.”
“to me this suggests that the performance gains from Project Valhalla in this Java will be minimal.”
“with Valhalla design now being merged into the language (Java 28+) we get explicit value types”
“If this alone is delivered I'd call Valhalla a success.”
“It transcends the binary understanding of object vs value and actually defines 4 distinct buckets”
“a beautiful specification that put semantics and performance payoff first and syntax seconds”
“can't wait for Project Valhalla, going into preview shortly”
“Valhalla can't come soon enough.”
“This beaurcratic development feels like turning a super-tanker that's connected to a hundred other super-tankers.”
“This is what makes the nuances of Valhalla's Value types so compelling.”
“So, this basically makes every value-object optional, adds extra overhead and makes code less safe to null pointer dereference errors.”
“after a few paragraphs it became clear this was either fed through an LLM or worse”
“Luckily we have Valhalla, which is an admission that Gosling was partially wrong”
“Scalarization can fail in surprising ways just due to what a maximal atomic write can be on the target platform”
“At what cost? A key benefit of value types is improved performance but AFAIK Valhalla doesn't even let you pass them by reference.”
“Which is why this is the wrong approach. Again. This is a major misstep.”
“It will make it really hard to extract a lot of the benefit of valhala if you can't make a thread unsafe value class.”
“I fail to see the point of this entire project”
“dang this is freaking cool!!!”
“this is anyway an extremely limited perf enhancement”
“Valhalla brings features that address key problems, and they didn’t rush to it either.”
“I think this alone shows this project can’t ever be turned on by default”
“it's nice to see Valhalla finally beocming reality”
“Oversimplifying a big semantic and backend change to a huge codebase”
“they basically copied what .NET did from basically year 1, is not a good look”
“First step to an interesting direction of the language.”
“I think these enhancements are essential to keep the platform relevant.”
“they are really late to the party with this but it's good. The performance boost will be welcome”
“Valhalla removes the historical performance tax on tiny domain objects.”
“Afaik Project Valhalla still hasn't become mainstream even after almost _12_ years at this point”
“Project Valhalla will be the most significant change to the JVM in a very long time”
“But Valhalla has been a veeery long time coming.”
“C# doesn't need nearly as many massive changes like project Valhalla”
“You can start trying the first part of Project Valhalla today”
Counts come from 1,791,911 Hacker News comments labeled by Claude, November 2025 to October 2026, with data through October 31, 2026. Counts updated 2 Nov 2026. How we count. Report a mistake.