python2 线程基础

Posted 2021-01-24 0点0度

1，感谢菜鸟教程，

线程基础：导入，创建函数，创建线和运行

import thread
import time

# 为线程定义一个函数
def print_time(threadName, delay):
    count = 0
    while count < 5:
        time.sleep(delay)
        count += 1
        print "%s: %s" % (threadName, time.ctime(time.time()))


# 创建两个线程
try:
    thread.start_new_thread(print_time, ("Thread-1", 2,))    #函数名和它的两个参数
    thread.start_new_thread(print_time, ("Thread-2", 5,))
except:
    print "Error: unable to start thread"

while 1:
    pass
#两个线程会同时分别进行，一个每五秒打印一次，一个每2秒打印一次

2，threading

import threading
import time

exitFlag = 0

class myThread(threading.Thread):  # 继承父类 threading.Thread
    def __init__(self, threadID, name, counter):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter

    def run(self):  # 把要执行的代码写到 run 函数里面 线程在创建后会直接运行 run 函数，所以基本可以理解为threading中，function run里的函数会自动运行
        print "Starting " + self.name
        print_time(self.name, self.counter, 5)
        print "Exiting " + self.name

def print_time(threadName, delay, counter):    #这个是单独的一个函数
    while counter:
        if exitFlag:
            (threading.Thread).exit()
        time.sleep(delay)
        print "%s: %s" % (threadName, time.ctime(time.time()))
        counter -= 1

    # 创建新线程
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)

# 开启线程
thread1.start()
thread2.start()

print "Exiting Main Thread"

3，线程锁

import threading
import time
 
class myThread (threading.Thread):
    def __init__(self, threadID, name, counter):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter
    def run(self):
        print "Starting " + self.name
       # 上锁
        threadLock.acquire()
        print_time(self.name, self.counter, 3)
        # 释放锁
         threadLock.release()
 
def print_time(threadName, delay, counter):
    while counter:
        time.sleep(delay)
        print "%s: %s" % (threadName, time.ctime(time.time()))
        counter -= 1
 
threadLock = threading.Lock()    #这个应该是实例化一个方法或者对象
threads = []
 
# 创建新线程
 thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
 
# 开启新线程
 thread1.start()
thread2.start()
 
# 添加线程到线程列表，注意此处，两个线程添加到一个列表，所以先执行第一个，执行完成以后再执行第二个
 threads.append(thread1)
threads.append(thread2)
 
# 等待所有线程完成，结果是两个线程依次执行
 for t in threads:
    t.join()
print "Exiting Main Thread"

4，多个线程之间的同步用队列

import Queue
import threading
import time

exitFlag = 0


class myThread(threading.Thread):
    def __init__(self, threadID, name, q):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.q = q

    def run(self):
        print "Starting " + self.name
        process_data(self.name, self.q)
        print "Exiting " + self.name


def process_data(threadName, q):    #实际上就是单个线程轮换着对队列进行某个操作，
    while not exitFlag:
        queueLock.acquire()
        if not workQueue.empty():
            data = q.get()
            queueLock.release()
            print "%s processing %s" % (threadName, data)
        else:
            queueLock.release()
        time.sleep(1)


threadList = ["Thread-1", "Thread-2", "Thread-3"]
nameList = ["One", "Two", "Three", "Four", "Five"]
queueLock = threading.Lock()
workQueue = Queue.Queue(10)
threads = []
threadID = 1

# for循环创建新线程
for tName in threadList:
    thread = myThread(threadID, tName, workQueue)
    thread.start()
    threads.append(thread)
    threadID += 1

# 填充队列
queueLock.acquire()
for word in nameList:
    workQueue.put(word)
queueLock.release()

# 等待队列清空
while not workQueue.empty():
    pass

# 通知线程是时候退出
exitFlag = 1

# 等待所有线程完成
for t in threads:
    t.join()
print "Exiting Main Thread"
#实际上就是开三个线程清空了一个队列，线程轮流参与，实现线程之间的同步