setdeamon 设置 线程为守护线程， （lock线程锁， BoundedSemaphore，rlock递归锁 ） 三种锁

1.setdeamon 当主程序执行完时，子程序自动被销毁 ，内存自动被收回

例一：

import threading, time

def run(n):
    print('run %s'%n)
    time.sleep(1)
    print('task %s'%n)


t_objs = []

for i in range(10):
    m = threading.Thread(target=run, args=(i,))
    m.setDaemon(True)  #把m子进程设置为守护线程
    m.start()
    t_objs.append(m)

#for t in t_objs:
#   t.join()

结果并不会输出 time.sleep(1) 后面的东西，因为直接就跳过了，


例二：

线程之间的相互调用

import threading, time

def run(n):
    print('task run%s'%n)
    time.sleep(1.8)
    print('run %s'%n)


def main():
    for i in range(5):
        m = threading.Thread(target=run,args=(i,))
        m.start()
        m.join(1)   #等待第一个m执行一秒钟，一秒钟以后继续循环


my_thread = threading.Thread(target=main,args=())

my_thread.setDaemon(True)  #设置为守护程序
my_thread.start()



my_thread.join(timeout=2)


2.lock 线程锁 

lock 可以保证每次调用时，内部数据只被一个线程操作，保证了不会被重复赋值

例一

import threading

def add_number():
    lock.acquire()
    global  number
    number += 1
    lock.release()


number = 0
lock = threading.Lock()
m_objs = []
for i in range(10):
    m = threading.Thread(target=add_number, args=())
    m.start()
    m_objs.append(m)


for m in m_objs:
    m.join()

print(number)

3.threading.BoundedSemaphore 也是一种锁 输出多个线程的结果

例一

import threading, time

def run(n):
    semaphore.acquire()
    print('task run %s'%n)
    time.sleep(1)
    semaphore.release()


if __name__ == '__main__':
    semaphore = threading.BoundedSemaphore(5)
    for i in range(22):
        m = threading.Thread(target=run, args=(i,))
        m.start()


4.递归锁 一个大锁里存在着一把小锁

例一：

import threading, time

def run_1():
    rock.acquire()
    print('run_1')
    rock.release()

def run_2():
    rock.acquire()
    print('run_2')
    rock.release()

def run():
    rock.acquire()
    run_1()
    time.sleep(1)
    run_2()
    rock.release()

if __name__ == '__main__':

    rock = threading.RLock()

    m = threading.Thread(target=run,args=())
    m.start()