NAnateb2022·May 12, 2026Submission
jacobin: More than minimal Java 21 JVM writen in Go
3 points · Open discussionplatypusguy
jacobin
Go2023–2026
platypusguy / jacobin
jacobin
A more than minimal JVM written in Go and capable of running Java 21 classes.
7Distinct people
8Mentions
0Explicit recommenders
759GitHub stars
What to know before exploring
What it is
A more than minimal JVM written in Go and capable of running Java 21 classes.
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
No recommendation phrase was found in the indexed comments.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
No other repository is repeatedly linked in the same discussions.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:03:16 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year8 dated mentions
Observed mentions: 2023-01-31 21:34:06 UTC to 2026-05-12 15:40:56 UTC.
* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 6 | 0 | 6 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2025 | 2025-01-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2026 (partial) | 2026-01-01 00:00:00 UTC | 2027-01-01 00:00:00 UTC | 1 | 1 | 0 |
What Hacker News says
8 sourcesJacobin, a JVM for Java 21 written in go
Website: https://jacobin.org
GitHub: https://github.com/platypusguy/jacobin
In Ask HN: What are you working on? (September 2025)Most languages have “precise garbage collectors” that always know from runtime type info which bits of an object are and are not heap pointers.
Sometimes you see add-on “conservative garbage collectors” that have to assume any word might be a pointer if it looks like an aligned address in an allocated page. They can’t move objects to do compaction because they’re never sure which words are not pointers.
Jacobin stores an object with a slice of its field values (each boxed as “any”) and types, so Go’s precise GC would be able to trace them: https://github.com/platypusguy/jacobin/blob/main/src/object/...
In Jacobin: A more than minimal JVM written in GoI don't think you can even implement indirect threading in Go. Go supports neither computed goto nor mutually recursive tail-call optimization (only self-recursive).
Jump tables for switch statements was only implemented last year. If you squint that's close to indirect threading, but still with at least one unnecessary conditional per op.
For the curious, here's their giant switch: https://github.com/platypusguy/jacobin/blob/c508ec50f55ef381... In practice compilers have always been finicky when it comes to coaxing them to emit jump tables from switch statements, and I bet this is especially truly for Go.
In Jacobin: A more than minimal JVM written in GoThanks for your note. The package notes on Jacobin say that we strongly discourage folks from running it in its present form. There are enough features still to be implemented, that for anything but trivial classes, you won't have a good experience. TBH, we're about a year out (we think) from having a version we can solicit users to test.
Nonetheless, if you'd be kind enough to post the above error and the class you used into the GitHub Issues tracker [0], we'll definitely include it in our test suite and make sure whatever the problem is, it'll be corrected.
[0] https://github.com/platypusguy/jacobin/issues
In Jacobin: A more than minimal JVM written in GoI concur. Native methods have hardcoded implementations, wired up here, and there is nothing for java.lang.Thread:
https://github.com/platypusguy/jacobin/blob/18c541820cb73bda...
I couldn't figure out what happens if you invoke a native method that has not been set up like this.
In Jacobin: A more than minimal JVM written in GoNo. It’s using Go’s built in GC: https://github.com/platypusguy/jacobin#garbage-collection
In Jacobin: A more than minimal JVM written in GoThe link at the end of the article to the JVM written in Go is a cool project. The GH project is at https://github.com/platypusguy/jacobin
In Reducing technical debt by valuing comments as much as code