Run with crontab won't print pid

Setup: */1 * * * * sh dog.sh this line in crontab -e

import os
import re

CUT_OFF = 90

def get_cpu_load():
    cmd = "ps -Ao user,uid,comm,pid,pcpu --sort=-pcpu | head -n 2 | tail -1"
    response = os.popen(cmd, 'r').read()
    arr = re.findall(r'\S+', response)
    print(arr)
    needKill = float(arr[-1]) > CUT_OFF
    if needKill:
        r = os.popen(f"kill -9 {arr[-2]}")
        print('kill:', r)

if __name__ == '__main__':
    # Test CPU with 
    # $ stress --cpu 1
    # crontab -e
    # Every 1 min
    # */1 * * * * sh dog.sh
    # ctlr o, ctlr x
    # crontab -l
    print(get_cpu_load())

Running with crontab won't print the PID.

Set up the line */1 * * * * sh dog.sh in crontab -e.

import os
import re

CUT_OFF = 90

def get_cpu_load():
    cmd = "ps -Ao user,uid,comm,pid,pcpu --sort=-pcpu | head -n 2 | tail -1"
    response = os.popen(cmd, 'r').read()
    arr = re.findall(r'\S+', response)
    print(arr)
    needKill = float(arr[-1]) > CUT_OFF
    if needKill:
        r = os.popen(f"kill -9 {arr[-2]}")
        print('kill:', r)

if __name__ == '__main__':
    # Test CPU with
    # $ stress --cpu 1
    # crontab -e
    # Every 1 min
    # */1 * * * * sh dog.sh
    # ctlr o, ctlr x
    # crontab -l
    print(get_cpu_load())