To start your parallel application under debugger control, you need to have the environment variable IDB_HOME set to the directory that your debugger is in. When debugging an application launched by mpich, issue the following command at the shell, where N represents number of processes and application is the name of the MPP program you would like to debug:
% mpirun -dbg=idb -np N [other mpich options] application [application arguments] [-idb idb options]
Make sure that there is a file called mpirun_dbg.idb in the directory in which mpirun is located. Also note that the Intel IDB option -gdb is not yet supported under parallel debugging session.
When the debugger starts your parallel application, it detects and attaches to all of your application's processes. At this point, your application stops before executing any user code and the debugger displays a prompt.
You can now set any necessary breakpoints and use the continue command to continue the execution of your application.
When debugging an application launched by prun, issue the following command at the shell, where n is the number of processes and N is the number of nodes running the processes.
% $IDB_HOME/idb [idb options] -parallel `which prun` -n n -N N [other prun options] application [application arguments]