Parallel Debuggers are important tools when trying to eliminate bugs in parallel programs. Commercial parallel debuggers are expensive.
In this blog post I will show you a free and open source alternative which is good enough for education purposes and for small codes.
Suppose you want to debug the famous cpi.c code which computes an approximation to pi by a parallel numerical integration. This demo uses the free Data Display Debugger (ddd) which is based on gdb but has a nice GUI.
Step 1, compile: mpicc -g -o cpi ./cpi.c
Step 2, run (without a debugger): mpirun -np 2 ./cpi
The recepie below may not be the simplest but this is what I had discovered while learning this subject
From the browser which holds your certificate make a bakup that will save it in p12 format. If you are working under Windows, this is the right moment to FTP it to Linux where life are easier, then proceed from you Linux computer by converting the *.p12 certificate to *.pem format: