We need a way to express clearly how many parallel jobs emerge should use; while we have been using MAKEOPTS up to now, it cannot be easily used for non-make buildsystems (waf, scons) which also support parallel build.
My proposal is to create a new variable, get it to default to 1 if not set, and then use that as -j parameter for emake _before_ makeopts (this way users can still re-set make to use the load average and other alternatives.
Even though other buildsystems can use the load average, it would be a _huge_ improvement to have at least a static number of job setting!
Rejected for EAPI 5 and again for EAPI 6:
makeopts_jobs() and makeopts_loadavg() in multiprocessing.eclass provide similar functionality.