Groups in TotalView
TotalView organizes all processes and threads into groups, which provides a mechanism by which you can precisely select the processes and threads on which a command will operate. Some groups contain (possibly multi-threaded) processes, while others contain just threads. The creation of these process or thread groups is largely automatic and occurs in the debugger without explicit input from the user. TotalView uses these groups for any operations that involve multiple threads or processes.
These automatically created groups offer a set of useful collections of threads and processes that can be selected as the group of interest (GOI) for certain debugger commands. You can select these either in the UI via the Focus menu, or, for finer control, in the CLI by providing a P/T set parameter to the dfocus or other commands. (More on P/T sets later, but a P/T set is simply a list of arenas.)
The GOI is the group that was specified in the focus and will therefore determine the set of processes and threads affected by the command. Most commands define a default group that makes sense for the command. For example, execution commands (Go, Stop, Step, etc.) default to the Control Group, and data-oriented or breakpoint commands default to the Share Group.