标签：col release lex UNC 结束 rom src 两种 sleep
什么是线程
线程是应用程序中工作的最小单元,或者称之为微进程.它是进程的实际运作单位,一条线程指的是进程中一个单一顺序的控制流，一个进程中可以并发多个线程，每条线程并行执行不同的任务。
threading.currentThread(): 返回当前的线程变量。 threading.enumerate(): 返回一个包含正在运行的线程的list。正在运行指线程启动后、结束前，不包括启动前和终止后的线程。 threading.activeCount(): 返回正在运行的线程数量，与len(threading.enumerate())有相同的结果。 除了使用方法外，线程模块同样提供了Thread类来处理线程，Thread类提供了以下方法: run(): 用以表示线程活动的方法。 start():启动线程活动。 join([time]): 等待至线程中止。这阻塞调用线程直至线程的join() 方法被调用中止-正常退出或者抛出未处理的异常-或者是可选的超时发生。 setDaemon(True):守护主线程,跟随主线程退(必须要放在start()上方) isAlive(): 返回线程是否活动的。 getName(): 返回线程名。 setName(): 设置线程名。
开启线程的两种方式
from threading import Thread def f1(n): print("%s号线程"%n) def f2(n): print("%s号线程"%n) if __name__ == ‘__main__‘: p1 = Thread(target=f1,args=(1,)) p2 = Thread(target=f1, args=(2,)) p1.start() p2.start() print("主线程")
from threading import Thread class Mythread(Thread): def __init__(self,name): super(Mythread, self).__init__() self.name = name def run(self): print("%s号线程"%self.name) if __name__ == ‘__main__‘: p1 = Mythread("alex") p1.start() print("主线程")
查看线程的进程
import os from threading import Thread def f1(n): print("1号",os.getpid()) print(‘%s号线程任务‘%n) def f2(n): print(‘2号‘,os.getpid()) print(‘%s号线程任务‘%n) if __name__ == ‘__main__‘: t1 = Thread(target=f1,args=(1,)) t2 = Thread(target=f2,args=(2,)) t1.start() t2.start() print(‘主线程‘,os.getpid()) print(‘主线程‘)
验证线程数据共享
import time from threading import Thread num =100 def f1(): time.sleep(3) global num num = 3 print(‘子线程num‘,num) if __name__ == ‘__main__‘: t = Thread(target=f1) t.start() t.join() print("主线程中的num",num)
线程与进程的效率对比
# -*- coding:utf-8 -*- import time from threading import Thread from multiprocessing import Process def f1(): n = 10 for i in range(100): n+=i if __name__ == ‘__main__‘: t_s_time = time.time() t_list = [] for i in range(20): t = Thread(target= f1,) t.start() t_list.append(t) [tt.join() for tt in t_list] t_e_time = time.time() t_dir_time = t_e_time - t_s_time p_s_time = time.time() p_list = [] for i in range(20): p = Process(target=f1,) p.start() p_list.append(p) [pp.join() for pp in p_list] p_e_time = time.time() p_dir_time = p_e_time - p_s_time print("多线程执行时间:",t_dir_time) print("多进程执行时间:",p_dir_time)
守护线程
守护线程会等待主程序运行完毕后被销毁
运行完毕并非运行终止
import time from threading import Thread from multiprocessing import Process # 守护进程:主进程代码执行运行结束,守护进程随之结束 #守护线程:守护线程会等待所有非守护线程运行结束才结束 def f1(): time.sleep(2) print(‘1号进程‘) def f2(): time.sleep(3) print(‘2号进程‘) if __name__ == ‘__main__‘: t1 = Thread(target=f1,) t2 = Thread(target=f2,) t1.daemon = True t2.daemon = True t1.start() t2.start() print(‘主线程‘) # if __name__ == ‘__main__‘: # p1 = Process(target=f1,) # p2 = Process(target=f2,) # p1.daemon = True # p2.daemon = True # p1.start() # p2.start() # print("主进程")
GIL锁
GIL本质是一把互斥锁
# -*- coding:utf-8 -*- import time from threading import Lock ,Thread num =100 def f1(loc): loc.acquire() global num tmp = num tmp -= 1 time.sleep(0.001) num = tmp loc.release() if __name__ == ‘__main__‘: t_loc = Lock() t_list = [] for i in range(10): t = Thread(target=f1,args=(t_loc,)) t.start() t_list.append(t) [tt.join() for tt in t_list] print("主线程num",num)
from threading import Thread,Lock,RLock import time def f1(locA,locB): locA.acquire() print("f1>>>1号抢到了A锁") time.sleep(1) locB.acquire() print("f1>>>1号抢到了B锁") locB.release() locA.release() def f2(locA,locB): locB.acquire() print("f2>>>2号抢到了B锁") locA.acquire() time.sleep(1) print("f2>>>2号抢到了A锁") locA.release() locB.release() if __name__ == ‘__main__‘: locA = Lock() locB = Lock() t1 = Thread(target=f1,args=(locA,locB)) t2 = Thread(target=f2,args=(locA,locB)) t1.start() t2.start()
# -*- coding:utf-8 -*- from threading import Thread,Lock,RLock import time def f1(locA,locB): locA.acquire() print("f1>>>1号抢到了A锁") time.sleep(1) locB.acquire() print("f1>>>1号抢到了B锁") locB.release() locA.release() def f2(locA,locB): locB.acquire() print("f2>>>2号抢到了B锁") locA.acquire() time.sleep(1) print("f2>>>2号抢到了A锁") locA.release() locB.release() if __name__ == ‘__main__‘: locA = locB = RLock() t1 = Thread(target=f1,args=(locA,locB)) t2 = Thread(target=f2,args=(locA,locB)) t1.start() t2.start()
信号量Semaphore
import time,os from threading import Thread,Semaphore def func(): sm.acquire() print("get sm") time.sleep(1) sm.release() if __name__ == ‘__main__‘: sm = Semaphore(os.cpu_count()) for i in range(23): t = Thread(target=func) t.start()
Event
from threading import Event e = Event() #初始状态False print(e.is_set()) print(‘开始等待‘) e.set() #将事件对象的状态改为True # e.clear() #将事件对象的状态改为false e.wait() #当e对象的状态为False的时候会在这个地方阻塞,改为true之后就直接往下执行 print(‘结束‘)
标签：col release lex UNC 结束 rom src 两种 sleep
原文地址：https://www.cnblogs.com/xiaoqianbook/p/10263896.html
