I am saying something very simple that seems to have caused your head to explode. It is: you could write n+1map in Python using Twisted, or Ruby using EventMachine, or Erlang, and probably end up faster (not because of the language, but because you'd design for speed and the language doesn't matter) than nmap is in C.
This isn't a controversial statement. Nobody thinks nmap is the fastest possible scanner. To argue that n+1map should be written in C, you have to make a case for what aspect of a port scanner benefits from C. Which is why I pointed out: nmap doesn't even look I/O bound; it looks timer-bound. And in most cases, neither I/O-bound nor timer-bound programs benefit greatly from locality, cheaper copies, or (within reason) optimized memory allocation and layout.
I believe the problem is that you seem to be saying c should only be used when performance matters. They think the language choice is irrelevant and shouldn't have even been mentioned. Or so I believe.
For my part, I am an avid C programmer; it's my first language, and virtually the only one I used through the '90s. And I will say: you should avoid writing in C unless you need to. The cases I can come up with off the top of my head where it's necessary:
* When performance matters and can be gained through writing C code --- for instance, if you're compute-bound, or if you need fast access to data structures.
* When building incremental improvements to large C codebases --- ie, writing a loadable kernel module.
* When you're deploying in small-footprint environments.
What are the other cases where C makes sense?
I brought up the C thing not because I want to take potshots at what is probably my favorite language, but because a majority of the developers on HN don't write C, and you'd hate for them not to take a crack at competing with nmap because they had a faulty belief that they'd need to use C.
This isn't a controversial statement. Nobody thinks nmap is the fastest possible scanner. To argue that n+1map should be written in C, you have to make a case for what aspect of a port scanner benefits from C. Which is why I pointed out: nmap doesn't even look I/O bound; it looks timer-bound. And in most cases, neither I/O-bound nor timer-bound programs benefit greatly from locality, cheaper copies, or (within reason) optimized memory allocation and layout.