Internal logging within the kernel is a bit of a mess. There's a combination of java.util.logging (JUL), System.out, System.err, and SLF4J (via libraries; we kinda handled this one per #99 , routing it to JUL ) and no configuration for JUL. So...
- Switch all loggers (including System.out, System.err) in the kernel to SLF4J. We already have it in the stack anyways, might as well use it.
- Route to JUL at the very last moment (in
jjava-distro, and also in jjava-launcher)
- Bundle a JUL config that is compatible with the default Jupyter log format (single line, labeled as
[I 2025-10-19 17:03:44.292 logger_name]
- Unify logging everywhere (one exception - still keeping
System.err in magics, as this will send logs to the notebook, as we'd expect)
- Adjust logging levels in the core framework for less noise
Internal logging within the kernel is a bit of a mess. There's a combination of
java.util.logging(JUL), System.out, System.err, and SLF4J (via libraries; we kinda handled this one per #99 , routing it to JUL ) and no configuration for JUL. So...jjava-distro, and also injjava-launcher)[I 2025-10-19 17:03:44.292 logger_name]System.errin magics, as this will send logs to the notebook, as we'd expect)