Pitfall08-gunicorn SIGTERM

************************** linux commands
kill -9 <pid> # sigkill
kill -15 <pid> # sigterm
ps -elf
pstree -p
**************************
I am seeing a weird behavior where Gunicorn does not shutdown immediately when sent a SIGTERM. 

Do you have open connections when this happens? If so, that is expected. SIGTERM is a graceful shutdown and subject to the --graceful-timeout setting (default 30s).
No open connections !!!!!!!!!!!!!!!!

TERM: graceful shutdown
while loop, never end, so never shutdown.......

if not while loop, when the program of child process ends, it will gracefully shutdown, become zombie process if no single handler in parent process.........

so in summary, SIGTERM was successfully sent to the child process, because it is not forceful, it will wait the child process to finish its program and gracefully
shut down.


****************************************************************************************************************************************************************
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! the reason for it not shut down is due to the endless loop in the child process !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
****************************************************************************************************************************************************************


however, it can be shutdown using SIGTERM when running python on local machine........not on gunicorn though...........??????????????????????????????????????
moreover, if terminated/killed, no zombie process left in the process table ............................



application.py
import time
import multiprocessing
from listener import Listener
import os
import sys 
print('****************************************** start **********************************!!!!!')
all_active_process = {}
for opla_job in ['opla-123', 'opla-456', 'opla-789']:
    instance = Listener(opla_job)
    p = multiprocessing.Process(target=instance.get_stream, name=opla_job)
    p.start()
    print('new process created for: ', opla_job)
    all_active_process[opla_job] = p
    print('all active process:', all_active_process)
while True:
    print('main script: going to sleep for 2 seconds.............')
    time.sleep(2)
    print('waking up.............................................')
    
    
listener.py ############################# no infinite loop here
import time
class Listener:
    def __init__(self, opla_job_number):
        self.opla_job_number = opla_job_number


    def get_stream(self):
        for i in range(100):
            print(self.opla_job_number,i)
        time.sleep(60)
        print(f'{self.opla_job_number} sleep ends...............')