在程序中使用线程时,系统在停止时未接收到SIGTERM

我想创建一个python程序,它作为systemd服务运行。我想能优雅地阻止它。我遇到了一个奇怪的行为:当我使用线程时,python程序在 systemctl stop example.service ,但如果我不使用线程,一切都可以正常工作。示例如下:

没有线。(服务接收到SIGTERM信号并按预期停止):

import signal
import time
import threading
import sys

RUN=True

# catch SIGINT and SIGTERM and stop application
def signal_handler(sig, frame):
    global RUN
    print("Got signal: "+str(sig))
    RUN=False
signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)

# some working thread inside application
def my_thread():
    global RUN
    while RUN:
        print("sleep")
        time.sleep(1.0)

my_thread()
print("Done.")

用线。(程序不接收SIGTERM信号,超时后被SIGKILL强制终止):

import signal
import time
import threading
import sys

RUN=True

# catch SIGINT and SIGTERM and stop application
def signal_handler(sig, frame):
    global RUN
    print("Got signal: "+str(sig))
    RUN=False
signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)

# some working thread inside application
def my_thread():
    global RUN
    while RUN:
        print("sleep")
        time.sleep(1.0)

# wait for thread to complete and exit
t = threading.Thread(target=my_thread)
t.start()
t.join()
print("Done.")

系统服务文件:

[Unit]
Description=Example service

[Install]
WantedBy=multi-user.target

[Service]
ExecStart=/usr/bin/python /opt/program/main.py
TimeoutSec=60
Restart=on-failure
Type=simple
User=mixo
Group=mixo

只需说明一下:我的程序需要多个线程,所以即使我在程序中使用线程,我也希望能够优雅地停止服务。我做错什么了?