# -P max-procs
# Run up to max-procs processes at a time; the default is 1.
# If max-procs is 0, xargs will run as many processes as possible
# at a time. Use the -n option with -P; otherwise chances are
# that only one exec will be done.
seq 10 | xargs -P 28 -I % echo %
#> 8
#> 4
#> 1
#> 7
#> 6
#> 3
#> 2
#> 5
#> 9
#> 10