并发的多线程演示

import threading
import time


def run()
   print('你好'）
   time.sleep(2)

t1=threading.Thread(target=run,args=('t1',))
t2=threading.Thread(target=run.args=('t2',))
t1.start()
t2.start()

 继承式调用

import threading
import time

class MyThread(threading.Thread):
    def __init__(self,n):
        super(MyThread,self).__init__()
        self.n = n
    def run(self):
        print('runnint task',self.n)
t1=MyThread('t1')
t2=MyThread('t2')
t1.start()
t2.start()

 

mport threading
import time


def run(n):
    print('task',n)
    time.sleep(2)
    print('task done',n)
start_time=time.time()

t_jobs=[]  #存线程实例

for i in range(50):
    t =threading.Thread(target=run,args=('t-%s' %i,))
    t.start()
    t_jobs.append(t)  #为了不在这里阻塞后面线程的启动，先把t放到一个列表里面
for t in t_jobs:
    t.join()  #等待线程执行完成后
print('----------all threads has finished')
print('coast:',time.time()-start_time)

 守护线程，当把所有的子线程设置为守护线程后，当主程序退出后，所有的子线程也就自动退出（不会管子线程有没有执行完毕）

import threading
import time

def run(n):
    print('task',n)
    time.sleep(2)
    print('task done',n)
#start_time=time.time()
t_objs=[]
for i in range(50):
    t =threading.Thread(target=run,args=('t-%s' %i,))
    t.setDaemon(True)
    t.start()
    t_objs.append(t)
print('----------all threads has finished')

 信号量：允许多个线程同时修改数据

import threading
import time

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

if __name__ == '__main__':
    semaphore = threading.BoundedSemaphore(5)#最多允许5个线程同时允许
    for i in range(22):
        t = threading.Thread(target=run,args=(i,))
        t.start()
while threading.active_count( ) != 1:
    pass
else:
    print('------all threads done')