标签：pid 同步锁 作用 and thread 静态 两种 == time
第一种方式
# 第一种方式
# from threading import Thread
#
# def task(name):
# print(f'{name} is running')
#
# if __name__ == '__main__':
# t = Thread(target=task,args=('mcsaoQ',))
# t.start()
#
# print('主线程')第二种方式
from threading import Thread
class MyThread(Thread):
def run(self):
print(f'{self.name} is running')
if __name__ == '__main__':
t = MyThread()
t.start()
print('主线程')速度的对比
from threading import Thread
def task(name):
print(f'{name} is running')
if __name__ == '__main__':
t = Thread(target=task,args=('mcsaoQ',))
t.start()
print('主线程')
'''
线程绝对要比进程要快:
mcsaoQ is running
主线程
'''pid
# pid 进程号
from threading import Thread
import os
def task():
print(f'子线程: {os.getpid()}')
if __name__ == '__main__':
t = Thread(target=task,)
t.start()
print(f'主线程: {os.getpid()}')线程之间的共享资源
# from threading import Thread
#
# x = 1000
#
# def task():
# global x
# x = 0
#
#
# if __name__ == '__main__':
# t = Thread(target=task)
# t.start()
# # t.join()
# print(f'主线程: {x}')
# from threading import Thread
# import time
# x = 1000
#
# def task():
# time.sleep(3)
# print('子线程....')
#
#
# def main():
# print('111')
# print('222')
# print('333')
#
# #
# # task()
# # main()
#
# if __name__ == '__main__':
# t = Thread(target=task)
# t.start()
# # t.join()
# main()# from threading import Thread
# import threading
# import time
#
#
# def task(name):
# time.sleep(1)
# print(f'{name} is running')
# print(threading.current_thread().name)
#
#
#
# if __name__ == '__main__':
# for i in range(5):
# t = Thread(target=task,args=('mcsaoQ',))
# t.start()
# # 线程对象的方法:
# # time.sleep(1)
# # print(t.is_alive()) # 判断子线程是否存活 ***
# # print(t.getName()) # 获取线程名
# # t.setName('线程111')
# # print(t.getName()) # 获取线程名
#
# # threading模块的方法:
# # print(threading.current_thread().name) # MainThread
# # print(threading.enumerate()) # 返回一个列表 放置的是所有的线程对象
# print(threading.active_count()) # 获取活跃的线程的数量(包括主线程)
# print('主线程')守护:子线程守护主线程,
结束条件:守护线程必须等待主线程结束才结束,主线程必须等所有的非守护线程结束才能结束
from threading import Thread
import time
def foo():
print(123)
time.sleep(3)
print("end123")
def bar():
print(456)
time.sleep(1)
print("end456")
if __name__ == '__main__':
t1=Thread(target=foo)
t2=Thread(target=bar)
t1.daemon = True
t1.start()
t2.start()
print("main-------")进程由死锁与递归锁,与线程同理,
死锁: 是指两个或两个以上的进程或线程在执行过程中,因争夺资源而造成的一种互相等待的现象,若无外力作用,它们都将无法推进下去,此时称系统处于死锁状态或系统产生了死锁,这些永远在互相等待的进程称为死锁进程,如下就是死锁
from threading import Thread
from threading import Lock
import time
lock_A = Lock()
lock_B = Lock()
class MyThread(Thread):
def run(self):
self.f1()
self.f2()
def f1(self):
lock_A.acquire()
print(f'{self.name}拿到A锁')
lock_B.acquire()
print(f'{self.name}拿到B锁')
lock_B.release()
lock_A.release()
def f2(self):
lock_B.acquire()
print(f'{self.name}拿到B锁')
time.sleep(0.1)
lock_A.acquire()
print(f'{self.name}拿到A锁')
lock_A.release()
lock_B.release()
if __name__ == '__main__':
for i in range(3):
t = MyThread()
t.start()
print('主....')解决死锁的方法:递归锁,在python中为了支持同一线程中多次请求同一资源,Python提供了可重入锁RLock
RLock内部维护着一个Lock和counter变量,counter记录了acquire的次数,从而使得资源可以被多次require,直到一个线程所有的acquire都被release,其他线程才能获取资源,上面的例子如果使用RLock代替Lock,则不会发生死锁:
from threading import Thread
from threading import RLock
import time
lock_A = lock_B = RLock()
class MyThread(Thread):
def run(self):
self.f1()
self.f2()
def f1(self):
lock_A.acquire()
print(f'{self.name}拿到A锁')
lock_B.acquire()
print(f'{self.name}拿到B锁')
lock_B.release()
lock_A.release()
def f2(self):
lock_B.acquire()
print(f'{self.name}拿到B锁')
time.sleep(0.1)
lock_A.acquire()
print(f'{self.name}拿到A锁')
lock_A.release()
lock_B.release()
if __name__ == '__main__':
for i in range(10):
t = MyThread()
t.start()
print('主....')Semaphore管理一个内置的计数器,每当调用acquire()时内置计数器+1,调用release()时内置计数器-1,计数器不能小于0,当计数器为0时,acquire()将阻塞线程直到其他线程调用release(),
from threading import Thread
from threading import Semaphore
from threading import current_thread
import time
import random
sem = Semaphore(5)
def go_public_wc():
sem.acquire()
print(f'{current_thread().getName()} 上厕所ing')
time.sleep(random.randint(1,3))
sem.release()
if __name__ == '__main__':
for i in range(20):
t = Thread(target=go_public_wc)
t.start()标签：pid 同步锁 作用 and thread 静态 两种 == time
原文地址：https://www.cnblogs.com/W-Y-C/p/11238755.html
