TotalView Users Guide - CI Wiki

Setting Breakpoints and Barriers
This means that if you do not want to share breakpoints in children that
use the same executable, dive into the breakpoints and set the breakpoint
options.
5 Select the Group > Go command.
Example: Multi-process Breakpoint
The following program excerpt illustrates the places where you can set
breakpoints in a multi-process program:
1 pid = fork();
2 if (pid == –1)
3 error ("fork failed");
4 else if (pid == 0)
5 children_play();
6 else
7 parents_work();
The following table describes what happens when you set a breakpoint at
different places:
Line Number Result
1 Stops the parent process before it forks.
2 Stops both the parent and child processes.
3 Stops the parent process if the fork() function failed.
5 Stops the child process.
7 Stops the parent process.
Setting Barrier Points
A barrier breakpoint is similar to a simple breakpoint, differing only in that
it holds processes and threads that reach the barrier point. Other processes
and threads continue to run. TotalView holds these processes or
threads until all processes or threads defined in the barrier point reach this
same place. When the last one reaches a barrier point, TotalView releases
all the held processes or threads. In this way, barrier points let you synchronize
your program’s execution.
CLI: dbarrier
Topics in this section are:
� “About Barrier Breakpoint States” on page 363
� “Setting a Barrier Breakpoint” on page 363
� “Creating a Satisfaction Set” on page 364
� “Hitting a Barrier Point” on page 365
� “Releasing Processes from Barrier Points” on page 365
� “Deleting a Barrier Point” on page 365
� “Changing Settings and Disabling a Barrier Point” on page 365
362 Chapter 16: Setting Action Points