Dynamic adjustments of build dependencies for the number of available processors

[SF Markus Elfring]

Hello,

I would like to use all processor cores for a software build.
So I try to reuse a corresponding system setting by a command
like "getconf _NPROCESSORS_ONLN" in recipes for a make file.

A bit of build preparation needs to be performed in a serial
way before I can begin the desired parallel data processing
with starting of some single-threaded programs for
background execution.

Such a system setting can vary during the run time of the
affected computing environment.
So I need to be flexible with the specification of input and
output parameters for these programs. But I see some software
development challenges for this use case.

1. If I would use a specific file name pattern here,
   I guess that they will also be needed for the
   dependency list of make targets.
   How should I create make targets in a consistent way
   on demand?

2. The return/exit code needs to recorded in dedicated files
   for the background processes so that their results can
   be safely checked in recipes later on.

   But I need to fiddle with several output files as
   a consequence for a specific target.
   How should I handle corresponding open issues then?

   * "a syntax for multitarget rules"
     by Reinier Post
     http://lists.gnu.org/archive/html/help-make/2014-11/msg00013.html

   * "Rules With Multiple Outputs in GNU Make"
     by Eric Melski
     http://www.cmcrossroads.com/article/rules-multiple-outputs-gnu-make


I would appreciate your ideas and further advices.

Regards,
Markus