ntpsec unsets MAKEOPTS. I have repeatedly built ntpsec without this in tmpfs on a 12-core cpu and have not been able to produce a parallel-build failure. git blame fingers this commit in the -9999 ebuild as the place where it was first introduced: https://github.com/gentoo/gentoo/commit/8b1d82cd97939eca1f801304c9a516533b1b9a9f Maybe it was a transient failure fixed in later git versions? Difference in build times on Ryzen 9 3900X: unset MAKEOPTS real 1m54,226s user 1m40,297s sys 0m20,287s MAKEOPTS=-j24 real 0m29,581s user 2m27,881s sys 0m29,170s Reproducible: Always
IMO not an NTPsec issue. NTPsec does not respect GNU autoscrap MAKEOPTS. Kick it over to the waf eclass maintainer(s) and ask them to handle it, or write and become the maintenance slave for autoscrap build if you are so inclined.