Availability:built-in
thread_setconcurrency(-Old,
+New)Determine the concurrency of the process,
which is defined as the maximum number of concurrently active threads.‘Active'
here means they are using CPU time. This option is provided if the
thread implementation provides pthread_setconcurrency(). Solaris is a
typical example of this family. On other systems this predicate unifies Old
to 0 (zero) and succeeds silently.