Comment by rbanffy
11 hours ago
I get the impression configure not only runs sequentially, but incrementally, where previous results can change the results of tests run later. Were it just sequential, running multiple tests as separate processes would be relatively simple.
Also, you shouldn’t need to run ./configure every time you run make.
No, but if you are doing something like rebuilding a distro's worth of packages from source from scratch, the configure step starts to dominate. I build around 550, and it takes around 6 hours on a single node.
Most checks are common, so what can help is having a shared cache for all configure scripts so if you have 400 packages to rebuild, it doesn't check 400 times if you should use flock or fcntl. This approach is described here: https://jmmv.dev/2022/06/autoconf-caching.html
It doesn't help that autoconf is basically abandonware, with one forlorn maintainer trying to resuscitate it, but creating major regressions with new releases: https://lwn.net/Articles/834682/
> It doesn't help that autoconf is basically abandonware
A far too common tragedy of our age.