Modes

Debug mode shows everything. Timing mode shows just elapsed time.

Available modes

debug (default)

Args, return values, exceptions, and timing — all in one JSON line:

JACKKNIFE {"event":"call","time":"12.3us","class":"Foo","method":"bar","args":["hello"],"return":"world"}

timing

Elapsed time and status only. No args or return values:

JACKKNIFE {"event":"call","time":"12.3us","class":"Foo","method":"bar","status":"returned"}

Selecting a mode

mvn jackknife:instrument -Dclass=com.example.Foo -Dmethod=bar -Dmode=timing

When to use timing

• Performance profiling — find slow methods without the noise of arg/return data
• Finding bottlenecks — narrow down which method in a call chain is expensive
• Lightweight observation — when you know what the method does and just need to know how long it takes