I've never seen segmentation faults in Perl apps, so I'd guess the problem is between the inline CPP code and the CPP program itself.

The "best debugger" is assuming everything's going to go...

If you need results in real time:

If, from Perl, the C++ spawn call is syncronous, you'll have to spawn the C++ app hundreds or more times, losing your speed advantage, and outputing the result...