TotalView Users Guide - CI Wiki

Setting Group Focus
� Lockstep Group
Contains every stopped thread in a share group that has the same PC.
TotalView creates one lockstep group for every thread. For example, suppose
two threads are stopped at the same PC. TotalView creates two lockstep
groups. While each lockstep group has the same two members, they
differ in that each has a different TOI. While there are some circumstances
where this is important, you can usually ignore this distinction. That is,
while two lockstep groups exist if two threads are stopped at the same
PC, ignoring the second lockstep group is almost never harmful.
The group ID value for a lockstep group differs from the ID of other
groups. Instead of having an automatically and transient integer ID, the
lockstep group ID is pid.tid, where pid.tid identifies the thread with which
it is associated. For example, the lockstep group for thread 2 in process
1 is 1.2.
In general, if you’re debugging a multi-process program, the control group
and share group differ only when the program has children that it forked
with by calling the execve() function.
Specifying Groups in P/T Sets
This section extends the arena specifier syntax to include groups.
If you do not include a group specifier, the default is the control group. For
example, the CLI only displays a target group in the focus string if you set it
to something other than the default value.
You most often use target group specifiers with the stepping commands, as they give
these commands more control over what’s being stepped.
Use the following format to add groups to an arena specifier:
[width_letter][group_indicator][pid][.tid]
This format adds the group_indicator to what was discussed in “Specifying Processes
and Threads” on page 259.
In the description of this syntax, everything appears to be optional. But,
while no single element is required, you must enter at least one element.
TotalView determines other values based on the current focus.
TotalView lets you identify a group by using a letter, number, or name.
A Group Letter You can name one of TotalView’s predefined sets. Each set is identified by a
letter. For example, the following command sets the focus to the workers
group:
dfocus W
TotalView Users Guide: version 8.7 263