cgdb allows full-featured gdb debugging of Cplant compute processes on a node-by-node basis from the service node.
cgdb is really a front end to a portals proxy for gdb running on the compute node.
Use of this feature MUST be done in conjunction with the attach option to yod:
% yod -sz 11 -attach hello
When run this way, yod displays a rank-to-node-id mapping of the job and prompts the user for input before allowing the compute processes to proceed to main. At this time one can connect to individual processes using instances of cgdb (one per compute node):
% cgdb -n 24
cgdb takes a single node id as input (or -h for help). When cgdb is started it contacts the pct on the specified node requesting start up of a portals proxy for gdb. Then cgdb contacts the proxy and requests that gdb be attached to the compute process. A standard gdb debugging session can be then performed over the pipe between cgdb and the proxy.