A share group is all processes associated with a given executable. In most cases, your program will be defined by a single executable, in which case the control group, which is the group used at group width, consists of just one share group. If, however, your program uses one or more other executables, the control group will consist of two or more share groups.

In this case, operations like stopping at a breakpoint do not apply to all processes and threads in the control group, but rather to all processes and threads in the share group to which the TOI belongs. This is because the processes and threads in the other share groups cannot stop at the breakpoint since it is not in the code they are executing.