At my tinderbox I do have: /etc/portage/env/noconcurrent MAKEOPTS="-j 1" NINJAFLAGS="-j 1" EGO_BUILD_FLAGS="-p 1" GOMAXPROCS="1" GO19CONCURRENTCOMPILATION=0 RUSTFLAGS="-C codegen-units=1" RUST_TEST_THREADS=1 RUST_TEST_TASKS=1 but the attached process table shows hat there're 12 perl jobs in parallel.
Created attachment 521964 [details] 18.1519888741 pstree
Maybe the perl bits aren't honoring it; the rest of the build process should. I don't think that part is dominated in the build time at all, but was significant enough that they made it parallel (maybe not making it follow ninja -j values in the process)
Is this still a problem?