kill 进程卡住，超时kill方法

还是有漏洞 ，万一 working.py未超时，  kill_job.sh 会不会杀死别人的进程啊
start.sh#!/bin/bash

python working.py &
python working.py &
python working.py &

pids=$(jobs -p)
echo $pids
sh kill_job.sh $pids &

pids_1=$(jobs -p)
echo $pids_1

for job in $pids
do
    wait $job
done
kill $pids_1
echo 'complete'

kill_job.sh

#!/bin/bash

echo $ $ $
echo 'sleep 5 min , then kill jobs'
sleep
kill $
kill $
kill $

working.py

#!/usr/bin/env python
# --*-- coding:utf-8 --*--

import time
import datetime

while True:
    print datetime.datetime.now()
    print 'sleep 1000 s'
    time.sleep(30)
    print 'complete'