worker pool in bash

worker_pool_example.sh

#!/bin/bash

THREADS=3

worker()
{
    echo "thread $1 starting"
    sleep 3
    rm -f /tmp/lock.$1
    echo "thread $1 finished"
}

for i in $(seq 10); do
    [ $(ls /tmp/lock.* 2>/dev/null|wc -l) -ge $THREADS ] && {
	echo "$THREADS threads already running, waiting for one to finish">&2
	sleep 1
	continue
    }
    lock=$RANDOM
    worker $lock &
    touch /tmp/lock.$lock
    echo "started thread $lock"
done