Launch a bunch of tasks concurrently

cm.zsh

#!/bin/env zsh
TASKS="${TASKS:=100}"
CONCURRENCY="${CONCURRENCY:=8}"
main()
{
    for t in `seq $TASKS`
    do
        $@ $t &
        while [ $(ps --no-headers -o pid --ppid=$$ | wc -w) -gt $CONCURRENCY ]
        do
            sleep 1    
        done
    done
}
if [ $# -eq 0 ]
then
    echo "cm: to what do I owe the extreme pleasure of this visit?"
else 
    main $@
fi
exit 0

Typing TASKS=10 CONCURRENCY=1 ./cm.zsh echo into the command line should get you started.