Any better alternative to fork() and then execvp(" gcc program.c ") ?

Question

Hi,

The following code segment takes more time (5s) when it is run first time and takes less time(250ms) on consecutive runs. Is there any better way to execute gcc.

int pid,status;
char * argv[] = {"gcc","program.c",NULL};
if(!(pid=fork())){
    execvp("gcc",argv);
}
while(pid!=wait(&status)){
    //do nothing
}

Answer 1

There's no other way to do it that would run across different Unix versions. To run a separate process you have to use fork-exec - that's exactly what they are made for.

Answer 2

Well, I don't think so. 5 seconds on the first go is probably time to read everything from disk to memory. The compiler itself, the sources to compile, the headers to include, libraries to link against etc. It's scattered all across the disk, so the disk heads have to seek a lot. That's slow.

After that you have all the data cached in RAM, it's just parsing and compilation and probably becomes CPU boudn rather than disk IO bound.

Answer 3

There are other functions you can call (std::system being one), but they generally end up being implemented as fork and exec.