python–threading多线程总结[通俗易懂]

# coding:utf-8
import threading import time #方法一：将要执行的方法作为参数传给Thread的构造方法
def action(arg): time.sleep(1) print 'the arg is:%s\r' %arg for i in xrange(4): t =threading.Thread(target=action,args=(i,)) t.start() print 'main thread end!'

#方法二：从Thread继承，并重写run()
class MyThread(threading.Thread): def __init__(self,arg): super(MyThread, self).__init__()#注意：一定要显式的调用父类的初始化函数。
        self.arg=arg def run(self):#定义每个线程要运行的函数
        time.sleep(1) print 'the arg is:%s\r' % self.arg for i in xrange(4): t =MyThread(i) t.start() print 'main thread end!'

# coding:utf-8
import threading import time def action(arg): time.sleep(1) print  'sub thread start!the thread name is:%s\r' % threading.currentThread().getName() print 'the arg is:%s\r' %arg time.sleep(1) for i in xrange(4): t =threading.Thread(target=action,args=(i,)) t.start() print 'main_thread end!'

main_thread end! sub thread start!the thread name is:Thread-2 the arg is:1 the arg is:0 sub thread start!the thread name is:Thread-4 the arg is:2 the arg is:3 Process finished with exit code 0 可以看出，创建的4个“前台”线程，主线程执行过程中，前台线程也在进行，主线程执行完毕后，等待前台线程也执行完成后，程序停止

# coding:utf-8
import threading import time def action(arg): time.sleep(1) print  'sub thread start!the thread name is:%s\r' % threading.currentThread().getName() print 'the arg is:%s\r' %arg time.sleep(1) for i in xrange(4): t =threading.Thread(target=action,args=(i,)) t.setDaemon(True)#设置线程为后台线程
 t.start() print 'main_thread end!'

main_thread end!

Process finished with exit code 0

可以看出，主线程执行完毕后，后台线程不管是成功与否，主线程均停止

#coding:utf-8
import threading import time def action(arg): time.sleep(1) print  'sub thread start!the thread name is:%s ' % threading.currentThread().getName() print 'the arg is:%s ' %arg time.sleep(1) thread_list = []    #线程存放列表
for i in xrange(4): t =threading.Thread(target=action,args=(i,)) t.setDaemon(True) thread_list.append(t) for t in thread_list: t.start() for t in thread_list: t.join()

sub thread start!the thread name is:Thread-2 the arg is:1 sub thread start!the thread name is:Thread-3 the arg is:2 sub thread start!the thread name is:Thread-1 the arg is:0 sub thread start!the thread name is:Thread-4 the arg is:3 main_thread end! Process finished with exit code 0 设置join之后，主线程等待子线程全部执行完成后或者子线程超时后，主线程才结束

#coding:utf-8
import threading import time def action(arg): time.sleep(1) print  'sub thread start!the thread name is:%s ' % threading.currentThread().getName() print 'the arg is:%s ' %arg time.sleep(1) for i in xrange(4): t =threading.Thread(target=action,args=(i,)) t.setDaemon(True) t.start() t.join() print 'main_thread end!'

sub thread start!the thread name is:Thread-1 the arg is:0 sub thread start!the thread name is:Thread-2 the arg is:1 sub thread start!the thread name is:Thread-3 the arg is:2 sub thread start!the thread name is:Thread-4 the arg is:3 main_thread end! Process finished with exit code 0 可以看出此时，程序只能顺序执行，每个线程都被上一个线程的join阻塞，使得“多线程”失去了多线程意义。

#coding:utf-8
import threading import time gl_num = 0 def show(arg): global gl_num time.sleep(1) gl_num +=1
    print gl_num for i in range(10): t = threading.Thread(target=show, args=(i,)) t.start() print 'main thread stop'

main thread stop 12

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568
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910 Process finished with exit code 0 多次运行可能产生混乱。这种场景就是适合使用锁的场景。

# coding:utf-8

import threading import time gl_num = 0 lock = threading.RLock() # 调用acquire([timeout])时，线程将一直阻塞， # 直到获得锁定或者直到timeout秒后（timeout参数可选）。 # 返回是否获得锁。
def Func(): lock.acquire() global gl_num gl_num += 1 time.sleep(1) print gl_num lock.release() for i in range(10): t = threading.Thread(target=Func) t.start()

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10 Process finished with exit code 0 可以看出，全局变量在在每次被调用时都要获得锁，才能操作，因此保证了共享数据的安全性

#coding:utf-8

import threading
lock = threading.Lock() #Lock对象
lock.acquire()
lock.acquire()  #产生了死锁。
lock.release()
lock.release()
print lock.acquire()


import threading
rLock = threading.RLock()  #RLock对象
rLock.acquire()
rLock.acquire() #在同一线程内，程序不会堵塞。
rLock.release()
rLock.release()

# encoding: UTF-8
import threading import time # 商品
product = None # 条件变量
con = threading.Condition() # 生产者方法
def produce(): global product if con.acquire(): while True: if product is None: print 'produce...' product = 'anything'

                # 通知消费者，商品已经生产
 con.notify() # 等待通知
 con.wait() time.sleep(2) # 消费者方法
def consume(): global product if con.acquire(): while True: if product is not None: print 'consume...' product = None # 通知生产者，商品已经没了
 con.notify() # 等待通知
 con.wait() time.sleep(2) t1 = threading.Thread(target=produce) t2 = threading.Thread(target=consume) t2.start() t1.start()

produce... consume... produce... consume... produce... consume... produce... consume... produce... consume... Process finished with exit code -1 程序不断循环运行下去。重复生产消费过程。

import threading import time condition = threading.Condition() products = 0 class Producer(threading.Thread): def run(self): global products while True: if condition.acquire(): if products < 10: products += 1; print "Producer(%s):deliver one, now products:%s" %(self.name, products) condition.notify()#不释放锁定，因此需要下面一句
 condition.release() else: print "Producer(%s):already 10, stop deliver, now products:%s" %(self.name, products) condition.wait();#自动释放锁定
                time.sleep(2) class Consumer(threading.Thread): def run(self): global products while True: if condition.acquire(): if products > 1: products -= 1
                    print "Consumer(%s):consume one, now products:%s" %(self.name, products) condition.notify() condition.release() else: print "Consumer(%s):only 1, stop consume, products:%s" %(self.name, products) condition.wait(); time.sleep(2) if __name__ == "__main__": for p in range(0, 2): p = Producer() p.start() for c in range(0, 3): c = Consumer() c.start()

import threading alist = None condition = threading.Condition() def doSet(): if condition.acquire(): while alist is None: condition.wait() for i in range(len(alist))[::-1]: alist[i] = 1 condition.release() def doPrint(): if condition.acquire(): while alist is None: condition.wait() for i in alist: print i, print condition.release() def doCreate(): global alist if condition.acquire(): if alist is None: alist = [0 for i in range(10)] condition.notifyAll() condition.release() tset = threading.Thread(target=doSet,name='tset') tprint = threading.Thread(target=doPrint,name='tprint') tcreate = threading.Thread(target=doCreate,name='tcreate') tset.start() tprint.start() tcreate.start()

# encoding: UTF-8
import threading import time event = threading.Event() def func(): # 等待事件，进入等待阻塞状态
    print '%s wait for event...' % threading.currentThread().getName() event.wait() # 收到事件后进入运行状态
    print '%s recv event.' % threading.currentThread().getName() t1 = threading.Thread(target=func) t2 = threading.Thread(target=func) t1.start() t2.start() time.sleep(2) # 发送事件通知
print 'MainThread set event.' event.set()

Thread-1 wait for event... Thread-2 wait for event... #2秒后。。。
MainThread set event. Thread-1 recv event. Thread-2 recv event. Process finished with exit code 0

# encoding: UTF-8
import threading def func(): print 'hello timer!' timer = threading.Timer(5, func) timer.start()

# encoding: UTF-8
import threading local = threading.local() local.tname = 'main'
 
def func(): local.tname = 'notmain'
    print local.tname t1 = threading.Thread(target=func) t1.start() t1.join() print local.tname

notmain
main