代码语言：javascript复制
#!/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 '------>',NUMEvent
代码语言：javascript复制#_*_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 ' 33[42;1m--green light on--- 33[0m'
elif count <13:
print ' 33[43;1m--yellow light on--- 33[0m'
elif count <20:
if event.isSet():
event.clear() #clear the green light , switch on the red light
print ' 33[41;1m--red light on--- 33[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
代码语言：javascript复制#_*_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 numRlock
代码语言：javascript复制#_*_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 numsemaphore#_*_coding:utf-8_*_
__author__ = 'gaogd'
import threading,time
def run(n):
semaphore.acquire()
time.sleep(1)
print "run the thread: %sn" %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
'''
