import threading
import time
def fun():
    for i in range(3):
        print("fun : %d"%i)
        print("[fun]",threading.active_count(), len(threading.enumerate()), threading.enumerate())
        time.sleep(1)

th1 = threading.Thread(target=fun)
th1.setDaemon(False)
th1.start()

for i in range(3):
    print("main : %d"%i)
    print("[main]",threading.active_count(), len(threading.enumerate()), threading.enumerate())

    time.sleep(0.5)
        

# th1.setDaemon(True) 时
fun : 0
main : 0
[fun] 2 2 [<_MainThread(MainThread, started 8607211008)>, <Thread(Thread-1, started daemon 12945776640)>]
[main] 2 2 [<_MainThread(MainThread, started 8607211008)>, <Thread(Thread-1, started daemon 12945776640)>]
main : 1
[main] 2 2 [<_MainThread(MainThread, started 8607211008)>, <Thread(Thread-1, started daemon 12945776640)>]
fun : 1
[fun] 2 2 [<_MainThread(MainThread, started 8607211008)>, <Thread(Thread-1, started daemon 12945776640)>]
main : 2
[main] 2 2 [<_MainThread(MainThread, started 8607211008)>, <Thread(Thread-1, started daemon 12945776640)>]：

# th1.setDaemon(False) 时
fun : 0
main : 0
[fun] 2 2 [<_MainThread(MainThread, started 8636325376)>, <Thread(Thread-1, started 13005135872)>]
[main] 2 2 [<_MainThread(MainThread, started 8636325376)>, <Thread(Thread-1, started 13005135872)>]
main : 1
[main] 2 2 [<_MainThread(MainThread, started 8636325376)>, <Thread(Thread-1, started 13005135872)>]
fun : 1
[fun] 2 2 [<_MainThread(MainThread, started 8636325376)>, <Thread(Thread-1, started 13005135872)>]
main : 2
[main] 2 2 [<_MainThread(MainThread, started 8636325376)>, <Thread(Thread-1, started 13005135872)>]
fun : 2
[fun] 2 2 [<_MainThread(MainThread, stopped 8636325376)>, <Thread(Thread-1, started 13005135872)>]

结论：
1、th1.setDaemon(True)时，main结束，fun线束
2、th1.setDaemon(False)时，fun没有随着主线程退出，fun全部执行完才退出
3、th1.setDaemon(False)时，threading.active_count()=2, 但 main的状态是“.... stopped 8636325376)>....” stoped和active分别啥意思，没想明白...

--
修改:jlsthsdqyx FROM 111.197.116.*
FROM 111.197.116.*

【 在 giantman 的大作中提到: 】
: 开始学习python中的多线程，可是我发现按照书上的例子，将子线程的daemon无论设成True还是False，结果都一样，子线程都不能随主线程的结束而结束，而且每次运行，结果都不完全一样，不知道是怎么回事？
: 程序如下：
: import threading
: ...................

我用 Python 3.7.3 在 Mac 平台下的 PyCharm IDE 中测试，结果完全符合预期. 可能你的Python环境有问题。
代码：
```
import sys
import threading
import time

print(f'\nPython version: {sys.version}\n', end='', flush=True)


def reading(msg: str):
    count = 3
    for i in range(count):
        print(f'{msg}: reading {i+1}/{count}\n', end='', flush=True)
        time.sleep(1)


def test(thread_count: int, is_daemon: bool) -> None:
    print(f'\n-------- setDaemon({is_daemon}) --------\n', end='', flush=True)
    for index in range(thread_count):
        r = threading.Thread(target=reading, args=[f'Thread {index+1}'])
        r.setDaemon(is_daemon)
        r.start()
    print('Main thread: The End\n', end='', flush=True)


test(5, True)

```

运行结果：
```
/Users/abc/project/pythonProject/test/venv/bin/python /Users/abc/project/pythonProject/test/my_daemon.py

Python version: 3.7.3 (default, Apr 24 2020, 18:51:23)
[Clang 11.0.3 (clang-1103.0.32.62)]

-------- setDaemon(True) --------
Thread 1: reading 1/3
Thread 2: reading 1/3
Thread 3: reading 1/3
Thread 4: reading 1/3
Thread 5: reading 1/3
Main thread: The End

Process finished with exit code 0
```

代码最后一行改为 `test(5, False)` 后，运行结果:
```
/Users/abc/project/pythonProject/test/venv/bin/python /Users/abc/project/pythonProject/test/my_daemon.py

Python version: 3.7.3 (default, Apr 24 2020, 18:51:23)
[Clang 11.0.3 (clang-1103.0.32.62)]

-------- setDaemon(False) --------
Thread 1: reading 1/3
Thread 2: reading 1/3
Thread 3: reading 1/3
Thread 4: reading 1/3
Thread 5: reading 1/3
Main thread: The End
Thread 1: reading 2/3
Thread 2: reading 2/3
Thread 5: reading 2/3
Thread 4: reading 2/3
Thread 3: reading 2/3
Thread 2: reading 3/3
Thread 5: reading 3/3
Thread 1: reading 3/3
Thread 3: reading 3/3
Thread 4: reading 3/3

Process finished with exit code 0

```
--
修改:galaxy123 FROM 74.88.40.*
FROM 74.88.40.*

多谢多谢。

不过我的运行结果和您的不同，而且True时，fun也还是在main之后全部运行完。

我用了两个环境测试（虽然结果中顺序不完全一致，但都是true时fun不能随main结束）：
一个是python 3.7.3（32-bit）,在IDLE中运行。第二个是spyder 5.0.3,里面的python好像是3.8.8 64-bit

【 在 jlsthsdqyx 的大作中提到: 】
: import threading
: import time
: def fun():
: ...................
--
FROM 1.95.148.*

多谢多谢，看了大家的回复后，我也逐渐感觉是我的运行环境有问题，准备换个pycharm试试。


【 在 galaxy123 的大作中提到: 】
:
: 我用 Python 3.7.3 在 Mac 平台下的 PyCharm IDE 中测试，结果完全符合预期. 可能你的Python环境有问题。
: 代码：
: ...................
--
FROM 1.95.148.*