I'm currently working on a social web application using python/django. Recently I heard about the PHP's weakness on large scale projects, and how hippo-php helped Facebook to overcome this barrier. Considering a python social web application with lot of utilization, could you please tell me if a similar custom tool could help this python application? In what way? I mean which portion (or layer) of application need to be written for example in c++? I know that it's a general question but someone with relevant experience I think that could help me.
Thank you in advance.
The portion to rewrite in C++ is the portion that is too slow in Python. You need to figure out where your bottleneck is, which you can do by load testing or just waiting until users complain.
Of course, even rewriting in C++ might not help. Your bottleneck might be the database (move to a separate, faster DB server or use sharding) or disk, or memory, or anything. Find bottleneck, work out how to eliminate bottleneck, implement. With 'test' inbetween all those phases. General advice.
There's normally no magic bullet, and I imagine Facebook did a LOT of testing and analysis of their bottlenecks before they tried anything.