`jinfo` - generate Java configuration information for a specified Java process

jinfo [-flag name | -flag [+|-]name | -flag name=value | -flags | -sysprops] pid

Options you will use

-flags: VM flags.
-flag <name>: One flag.
-flag +<name>: Set a MANAGEABLE flag at runtime (e.g. HeapDumpOnOutOfMemoryError). Anything else: "cannot be changed".
-sysprops: System properties.
-flag NAME: Print one flag; -flag +NAME / -NAME / NAME=VALUE changes a MANAGEABLE flag at runtime.

Examples

$ jinfo -flag MaxHeapSize 1210

$ jinfo -flag +HeapDumpOnOutOfMemoryError 1210

No restart needed - it is manageable.

Gotchas

ExitOnOutOfMemoryError is not manageable: it needs a restart.

Try jinfo in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.