Question

Given a simple script as the following, why is using daemon flag useful? Maybe this is too simple, but I understand that daemon threads are generally long running background tasks (they are not meant to be waited for as quoted by Raymond Hettinger). So, if I have a task that I am not waiting for and simply start a non-daemon thread and not join, is that psuedo-daemon? It seems the functionality runs the same. Or is this more of a question of memory than processing logic? With the second question Im actually not sure how much resources this script consumes in the aspects of daemon vs non-daemon


from threading import Thread 
import time
import sys
def func():
    for i in range(4):
        print(f"Running Thread-{i}")
        time.sleep(1)


t = Thread(target=func)
# t.daemon = True # nothing seems to change
t.start()
sys.exit()

Answer 1

重复增加清晰度。我认识到,当一个方案即将退出时,马丹马透镜显示其真实的肤色。思维方式,如 de魔,或廉价、无心的粉饰”,, 这里提及的是 , 谷歌,除非已经完工或未完成,否则将突然停止种植。因此,Daemon 如下文所述,“完成胎盘”和(或)等待/锁定(见.join(<>>>>/code>,Non-Daemons.,<>BUT,caveats <>/em>(或在此情况下,造成线形状的执行)。


Daemon = 非daemon on 2 conditions.

Here we are waiting for ALL THREADS. Although this "works", the daemon thread should just be a non-daemon. Flagging a thread as daemon, in this case, is giving instructions (to the code reader/maintiner as well) that  these threads all need to be waited for, which doesnt make much sense (and what Raymond said does make sense, "Dont wait for daemons")

# Psuedo-code

d_t = DaemonThread

n_t = NonDaemonThread

for thread_ in [d_t, n_t]:
  thread_.start() 

for thread_ in [d_t, n_t]:
  thread_.join() 

<>>>>

Here we aren t waiting for ANY threads. Not only does this imply that we dont need to wait for tasks BUT now the non-daemon threads, will be abruptly stopped when the program exits, since they are not waited for.

# Psuedo-code

d_t = DaemonThread

n_t = NonDaemonThread

for thread_ in [d_t, n_t]:
  thread_.start() 

# never call join()

我的混淆导致我的原职是2个部分。 我认为,终止方案(因此,包括sys.exit)与“自成一体”方案(案文是关键,但 da诉非mon,没有区别)之间可能有所不同,还有以下事实:有“主导”执行,你can>/em>等。 希望这能帮助人们理解沙捞越了一点!
Edit: 改进解释

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