Python 多线程 threading

4321oiuy

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#!/usr/bin/python # -*- coding: utf-8 -*- __author__ = 'gaogd' ''' ### 多进程 import threading import time def run(num):     print 'Hi, I am thread %s..lalala' % num     time.sleep(1) for i in range(20):   t = threading.Thread(target=run, args=(i,))   t.start() ''' ''' ##进程启动完20个线程就继续走下去,不等待这20个线程走完就回到住线程 import threading import time def run(num):     global NUM     time.sleep(1)     print 'Hi, I am thread %s..lalala' % num     NUM +=1 NUM = 0 for i in range(20):   t = threading.Thread(target=run, args=(i,))   t.start()      ## #time.sleep(2) print  '------>',NUM ''' ''' import threading import time def run(num):     global NUM     time.sleep(1)     print 'Hi, I am thread %s..lalala' % num     NUM +=1 NUM = 0 for i in range(20):     t = threading.Thread(target=run, args=(i,))     t.start()     t.join()      ##等子线程执行完再执行子线程。 print  '------>',NUM ''' ''' ###下面两百个线程时并发执行,但是共享内存有点问题 import threading import time def run(num):     global NUM     time.sleep(1)     print 'Hi, I am thread %s..lalala' % num     NUM +=1 NUM = 0 p_list = []    ##线程列表,追加线程实例 t 到这个列表 for i in range(500):     t = threading.Thread(target=run, args=(i,))     t.start()     p_list.append(t) for i in p_list:     t.join()      ##等待线程都执行完再执行这个,但是共享的内存有可能出现问题,所有出现NUM不一定等于500,没有加锁导致的问题,这就涉及安全了 print  '------>',NUM ''' import threading import time def run(num):     global NUM     time.sleep(1)     print 'Hi, I am thread %s..lalala' % num     lock.acquire()  ## 加锁     NUM +=1     lock.release()   ##释放锁,如果不释放,那后面的就都改不了数据了 NUM = 0 p_list = [] lock = threading.Lock()     ##生成一把锁 for i in range(500):     t = threading.Thread(target=run, args=(i,))     t.start()     p_list.append(t) for i in p_list:     t.join()      ##等待线程都执行完再执行这个,但是共享的内存有可能出现问题,所有出现NUM不一定等于200,没有加锁导致的问题,这就涉及安全了 print  '------>',NUM

Event

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#_*_coding:utf-8_*_ __author__ = 'jieli' import threading,time import random def light():     if not event.isSet():         event.set() #wait就不阻塞 #绿灯状态     count = 0     while True:         if count < 10:             print '\033[42;1m--green light on---\033[0m'         elif count <13:             print '\033[43;1m--yellow light on---\033[0m'         elif count <20:             if event.isSet():                 event.clear() #clear the green light , switch on the red light             print '\033[41;1m--red light on---\033[0m'         else:             count = 0             event.set() #打开绿灯         time.sleep(1)         count +=1 def car(n):     while 1:         time.sleep(random.randrange(3))         if  event.isSet(): #绿灯             print "car [%s] is running.." % n         else:# red light             print "car [%s] is waiting for the red light.." %n             event.wait()             print "Green light is on , car %s is running.............." %n if __name__ == '__main__':     event = threading.Event()     Light = threading.Thread(target=light)     Light.start()     for i in range(3):         t = threading.Thread(target=car,args=(i,))         t.start() ''' Events # An event is a simple synchronization object; the event represents an internal flag, and threads can wait for the flag to be set, or set or clear the flag themselves. event = threading.Event() # a client thread can wait for the flag to be set event.wait() # a server thread can set or reset it event.set() event.clear() If the flag is set, the wait method doesn’t do anything. If the flag is cleared, wait will block until it becomes set again. Any number of threads may wait for the same event. '''

lock

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#_*_coding:utf-8_*_ __author__ = 'jieli' import threading,time def run(n):     time.sleep(0.5)     global  num     lock.acquire() #申请锁并+锁     num +=1     lock.release() #释放锁 if __name__ == '__main__':     num = 0     lock = threading.Lock()     for i in range(1000):         t = threading.Thread(target=run,args=(i,))         t.start() while threading.active_count() != 1:     print threading.active_count() else:     print '----all threads done---'     print num

Rlock

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#_*_coding:utf-8_*_ __author__ = 'jieli' import threading,time def run1():     print "grab the first part data"     lock.acquire()     global num     num +=1     lock.release()     return num def run2():     print "grab the second part data"     lock.acquire()     global  num2     num2+=1     lock.release()     return num2 def run3():     lock.acquire()     res = run1()     print '--------between run1 and run2-----'     res2 = run2()     lock.release()     print res,res2 if __name__ == '__main__':     num,num2 = 0,0     lock = threading.RLock()     for i in range(10):         t = threading.Thread(target=run3)         t.start() while threading.active_count() != 1:     print threading.active_count() else:     print '----all threads done---'     print num

semaphore

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#_*_coding:utf-8_*_ __author__ = 'gaogd' import threading,time def run(n):     semaphore.acquire()     time.sleep(1)     print "run the thread: %s\n" %n     semaphore.release() if __name__ == '__main__':     num= 0     semaphore  = threading.BoundedSemaphore(5)     ### 5个令牌,也就是同一时间可以处理5个线程     for i in range(20):         t = threading.Thread(target=run,args=(i,))         t.start() while threading.active_count() >= 1:    ##现在还要多少个线程在启动     pass #print threading.active_count() else:     print '----all threads done---'     print num ''' 用途: 1.限制数据库的连接数 '''