© Richard Jones, University of Kent 2008http://www.cs.kent.ac.uk/~rej

ISMM 2008 Wild & Crazy Ideas 1

Richard JonesComputing Laboratory

University of Kent, Canterburyhttp://www.cs.kent.ac.uk/~rej

8 June 2008, Tucson AZ

Seeing Is Doing

ISMM 2008

© Richard Jones, University of Kent 2008http://www.cs.kent.ac.uk/~rej

ISMM 2008 Wild & Crazy Ideas 2

GCspy: GC Visualisation

Space 2

Control

Stream 0

Stream 1

Space 1

Control

Stream 0

Stream 1

Space 0

Control

Stream 0

Stream 1

Event filters Client Interpreter

OG driver

Control

Objects

Space

Free-list

Control

Free-lists

YG driver

Control

Objects

Space

Event filters Server Interpreter

Data gathering

YGCopying

GC

OGMark-Sweep

GC

Control

Connect

Pause

Step

Continue

Disconnect

Event filters• Enable/disable

• Pause at event

• Period

Data

© Richard Jones, University of Kent 2008http://www.cs.kent.ac.uk/~rej

ISMM 2008 Wild & Crazy Ideas 3

GCspy: GC Control

Space 2Space 1Space 0

Toggles

Sliders

Event filters Client Interpreter

OG driver

Callback

Free-list

Callback

YG driver

Callback

Event filters Server Interpreter

Data gathering

YGCopying

GC

OGMark-Sweep

GC

Control

Toggles

Sliders

Toggles

Sliders

Data

© Richard Jones, University of Kent 2008http://www.cs.kent.ac.uk/~rej

ISMM 2008 Wild & Crazy Ideas 4

Callbacks

Buttons and sliders in the visualiser (client side)

to set state in a driver (server side).

Drivers poll state

and modify collector’s operation.• Trigger full GC rather than minor GC.• Enable/disable logging.• Hot-swap GCs.• Expand/contract heap size.• Scan space rather than use remsets.• Pretenuring control.• Intelligent client (offline analysis and control).

© Richard Jones, University of Kent 2008http://www.cs.kent.ac.uk/~rej

ISMM 2008 Wild & Crazy Ideas 5

Questions?