cljbridge fails to create Java VM

[tjg]

This:
cljbridge.init_jvm(start_repl=True)

results in:
RuntimeError: Failed to create Java VM. Return code = -1

My context

• MacOS 15.7.2, Python 3.9.6
• tested with Java temurin@17 & temurin@21 (via brew install)

Error

At commandline:

% python3 -m venv .venv 
% source .venv/bin/activate
(.venv) % export PATH=/Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home/bin:$PATH
(.venv) % export JAVA_HOME=$(/usr/libexec/java_home -v 17) 
(.venv) % env | egrep 'JAVA|JDK'
JAVA_HOME=/Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home

(.venv) % python3 

At Python REPL:

Python 3.9.6 (default, Oct 17 2025, 17:15:53) 
[Clang 17.0.0 (clang-1700.4.4.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from clojurebridge import cljbridge
>>> test_var=10
>>> cljbridge.init_jvm(start_repl=True)
WARNING: Implicit use of clojure.main with options is deprecated, use -M -e (require '[clojure.tools.build.api :as b]'[clojure.string :as str])(let [basis (b/create-basis {:aliases (map keyword [])}) jvm-args (str/join " " (:jvm-opts (:resolve-args basis)))] (println jvm-args))
Unrecognized option: 
Failed to create Java virtual machine.

Traceback (most recent call last):
 File "/Users/foo/projects/myproject/mycodebase/.venv/lib/python3.9/site-packages/javabridge/jutil.py", line 282, in start_thread
 vm.create_mac(args, RQCLS, library_path, libjli_path)
 File "_javabridge.pyx", line 707, in _javabridge.JB_VM.create_mac
RuntimeError: Failed to create Java VM. Return code = -1
Failed to create Java VM
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/Users/foo/projects/myproject/mycodebase/.venv/lib/python3.9/site-packages/clojurebridge/cljbridge.py", line 170, in init_jvm
 javabridge.start_vm(run_headless=True,
 File "/Users/foo/projects/myproject/mycodebase/.venv/lib/python3.9/site-packages/javabridge/jutil.py", line 319, in start_vm
 raise RuntimeError("Failed to start Java VM")
RuntimeError: Failed to start Java VM

cljbridge version: 0.0.8

(.venv) % python3 -m pip install cljbridge
Requirement already satisfied: cljbridge in ./.venv/lib/python3.9/site-packages (0.0.8)

[behrica]

which version of cljbridge are you using ?
Your steps above miss how you install "clojure bridge" into your venv

[tjg]

Ah thanks @behrica for noticing, I used this, which installs 0.0.8:

python3 -m pip install cljbridge
Requirement already satisfied: cljbridge in ./.venv/lib/python3.9/site-packages (0.0.8)
...

Verifying that it installs 0.0.8 (which appears to be the latest version on PyPI):

(.venv) % pip show cljbridge
Name: cljbridge
Version: 0.0.8
Summary: An extension og python-javabridge to start Clojure
Home-page: https://github.com/behrica/clojurebridge
Author: Carsten Behring
Author-email: carsten.behring@gmail.com
License:
Location: /Users/foo/projects/myproject/mycodebase/.venv/lib/python3.9/site-packages
Requires: python-javabridge
Required-by:

I'll edit my original issue to include this info

[behrica]

I can confirm that it fails when uisng python 3.9.6, as you do.
Can you please try with Python 3.10.16 ?

[tjg]

Hmm, unfortunately it still doesn't work for me...

Set Python version:

% brew install pyenv
...
% pyenv global 3.10.16
% export PATH="$HOME/.pyenv/shims:$PATH"
% python --version 
Python 3.10.16

Run cljbridge:

% python3 -m pip show cljbridge
Name: cljbridge
Version: 0.0.8
...
Location: /Users/foo/.pyenv/versions/3.10.16/lib/python3.10/site-packages

% python3
Python 3.10.16 (main, Nov 22 2025, 20:22:55) [Clang 17.0.0 (clang-1700.4.4.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from clojurebridge import cljbridge
>>> cljbridge.init_jvm(start_repl=True)
WARNING: Implicit use of clojure.main with options is deprecated, use -M -e (require '[clojure.tools.build.api :as b]'[clojure.string :as str])(let [basis (b/create-basis {:aliases (map keyword [])}) jvm-args (str/join " " (:jvm-opts (:resolve-args basis)))] (println jvm-args))
Unrecognized option: 
Failed to create Java virtual machine.

Traceback (most recent call last):
 File "/Users/foo/.pyenv/versions/3.10.16/lib/python3.10/site-packages/javabridge/jutil.py", line 282, in start_thread
 vm.create_mac(args, RQCLS, library_path, libjli_path)
 File "_javabridge.pyx", line 707, in _javabridge.JB_VM.create_mac
RuntimeError: Failed to create Java VM. Return code = -1
Failed to create Java VM
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/Users/foo/.pyenv/versions/3.10.16/lib/python3.10/site-packages/clojurebridge/cljbridge.py", line 170, in init_jvm
 javabridge.start_vm(run_headless=True,
 File "/Users/foo/.pyenv/versions/3.10.16/lib/python3.10/site-packages/javabridge/jutil.py", line 319, in start_vm
 raise RuntimeError("Failed to start Java VM")
RuntimeError: Failed to start Java VM

[behrica]

I am not familar with MacOs at all.
Maybe @cnuernber can have a look.

I see that lately the tests on MacOS fail:
https://github.com/clj-python/libpython-clj/actions/runs/12223833394