（一）基础概念线程：是程序执行流的最小单元（线程内部可开线程）、每一个程序都至少有一个线程、线程共享统一进程中的所有资源。
进程：是最小的资源单元（内存资源的分配与调度）线程共享进程中的资源,(每个进程中至少有一个线程（QQ\360))
并发：是指系统具有执行多个任务（动作）的能力并行：是指系统具同一时刻进行多个任务（动作）的能力（是并发子集）
线程与进程关系：一个程序至少有一个进程、每个进程中至少有 一个线程
（1）线程的创建(threading接口)
（1）线程的创建(threading接口) 1.自己创建线程 # sampleOne import threading import time def Hi(name): print("Hello %s" %name) time.sleep(3) if __name__=="__main__": t1 = threading.Thread(target=Hi,args=("萌萌",)) t1.start() t2 = threading.Thread(target=Hi, args=("蒙蒙",)) t2.start() print("end")
2）线程的调用方式
2.创建线程类继承threading.Thread类下的方法 class Mythread(threading.Thread): def __init__(self, num): # threading.Thread.__init__(self) super().__init__() self.num = num def run(self): # music1() # game1() print("start num %d" % self.num) if __name__ == "__main__": t1 = Mythread(1) t2 = Mythread(2) t1.start() t2.start() （3）线程阻塞join方法
join:子线程完成之前主线程一直阻塞‘‘‘ def music(): print("begin to listen %s" %time.ctime()) time.sleep(3) print("stop to listen %s" % time.ctime()) def game(): print("begin to game %s" % time.ctime()) time.sleep(5) print("stop to game %s" % time.ctime()) if __name__ == "__main__": t1 = threading.Thread(target=music, ) t2 = threading.Thread(target=game, ) t1.start() t2.start() # t1.join() t2.join() print("over end ")
（4）线程的守护 setDaemon
‘‘‘setDaemon:线程守护、子线程跟随主线程一起退‘‘‘ def music1(): print("begin to listen %s" %time.ctime()) time.sleep(3) print("stop to listen %s" % time.ctime()) def game1(): print("begin to game %s" % time.ctime()) time.sleep(5) print("stop to game %s" % time.ctime()) if __name__ == "__main__": t1 = threading.Thread(target=music1, ) t2 = threading.Thread(target=game1, ) t2.setDaemon(True) t1.start() t2.start() （5）线程锁与递归锁、结果不是想要的、多个线程操作同一个对象是引发数据安全、只能借助线程锁threading.Lock()
# 开100个线程、每个线程对同一个数递减1 import time import threading def sub(): global num temp = num time.sleep(0.01) num = temp-1 if __name__=="__main__": num=100 for i in range(100): t = threading.Thread(target=sub) t.start() t.join()
‘‘‘针对线程安全问题创建线程同步锁‘、‘‘输出结果为0、是想要的结果、但有些情况锁也会带来负面的影响
def sub1(): global num lock.acquire() temp = num time.sleep(0.001) num = temp-1 lock.release() if __name__ =="__main__": num=100 lock=threading.Lock() for i in range(100): t = threading.Thread(target=sub1) t.start() t.join() print(num)
死锁
class Mythread(threading.Thread): def actionA(self): A.acquire() print(self.name, "got A", time.ctime()) B.acquire() print(self.name, "got B", time.ctime()) B.release() A.release() def actionB(self): B.acquire() print(self.name, "got B", time.ctime()) A.acquire() print(self.name, "got A", time.ctime()) A.release() B.release() def run(self): self.actionA() self.actionB() if __name__ == "__main__": L = [] A=threading.RLock() B=threading.RLock() for i in range(5): t = Mythread() t.start() L.append(t) for t in L: t.join() print("ending>>>>>>>>>>") （5）递归锁RLock()解决死锁问题
创建一把递归锁、替换上面的所有锁 r_lock=threading.RLock()
class Mythread(threading.Thread): ‘‘‘递归锁 解决死锁‘‘‘ def actionA(self): r_lock.acquire() # count=1 print(self.name, "got A", time.ctime()) r_lock.acquire() # 锁中锁 count=2 print(self.name, "got B", time.ctime()) r_lock.release() # count = 1 r_lock.release() # count = 0 def actionB(self): r_lock.acquire() print(self.name, "got B", time.ctime()) r_lock.acquire()# 锁中锁 print(self.name, "got A", time.ctime()) r_lock.release() r_lock.release() def run(self): self.actionA() self.actionB() if __name__ == "__main__": L = [] r_lock=threading.RLock() for i in range(5): t = Mythread() t.start() L.append(t) for t in L: t.join() print("ending>>>>>>>>>>")
需求：多个线程删除列表中的最后一个元素并删除
L=[1,3,45,65,76,32,3254] def pri(): while 1: a = L[-1] print(a) time.sleep(2) L.remove(a) # 按值来删除 # L.pop(-1) # 按照索引删除 t1=threading.Thread(target=pri,args=()) t1.start() t2=threading.Thread(target=pri,args=()) t2.start() 看运行结果、
（6）队列queue、是一种数据结构线程使用队列、数据是安全的
import queue Li=[] q=queue.Queue() # FIFO # # q =queue.LifoQueue()# LIFO # q =queue.PriorityQueue(4) # 优先级s q.put([4,234]) q.put_nowait([2,"hello"]) q.put([3,{"name","alex"}]) q.put([5,{"gendle":"女"}],) # q.put(78,block=False) # 队列已满时报错 # q.put_nowait(78) # 队列已满时报错 while 1: # data=q.get() data = q.get(block=False) # data =q.get_nowait() # 为空时报错 print(data) # print(q.qsize()) # print(q.empty()) # print(q.full()) # print(data[1]) time.sleep(1) print("----------") （7）同步对象Event、保证所有的线程中状态完全一致‘
import threading import time ‘‘‘同步对象Event 保证所有的线程中状态完全一致‘‘‘ class teacher(threading.Thread): def run(self): print("teacher: 明天把之前的作业留的作业都完成交上来") print("状态是否被设定",event.isSet()) event.set() time.sleep(5) print("teacher:既然这样那下周一交上来") event.set() class student(threading.Thread): def run(self): event.wait() # 一旦event.set() 则event.wait()==pass print("student:啊那么多怎么可能一天完成啊！！！！！") time.sleep(2) event.clear() event.wait() print("student:ohyear!!") if __name__ == "__main__": event = threading.Event() threads=[] for i in range(6): threads.append(student()) threads.append(teacher()) for t in threads: t.start() for t in threads: t.join() print("所有的都结束了")