python3 多线程下载 python多线程菜鸟教程

记录学习python线程相关的知识,参照菜鸟教程:https://www.runoob.com/python3/python3-multithreading.html

1.调用 _thread 模块中的start_new_thread()函数开启线程

import _thread
import time

def print_time(threadName, delay):
    count = 0
    while count < 5:
        time.sleep(delay)
        count += 1
        print("%s:%s" % (threadName,time.ctime(time.time())))

try:
    _thread.start_new(print_time,("thred-1", 2, ))
    _thread.start_new(print_time,("thred-2", 4, ))
except:
    print("error : 无法启动线程")

while 1:
    pass

2.使用 threading 模块创建线程

import threading
import time

exitFlag = 0
class myThread (threading.Thread):
    def __init__(self, thradId, name, count):
        threading.Thread.__init__(self)
        self.thradId = thradId
        self.name = name
        self.count = count
    def run(self):
        print("开始线程" + self.name)
        print_time(self.name,self.count, 5)
        print("退出线程" + self.name)
def print_time(threadName,delay,counter):
    while counter:
        if exitFlag:
            threadName.exit()
        time.sleep(delay)
        print("%s:%s" % (threadName, time.ctime(time.time())))
        counter -= 1

thrad1 = myThread(1,"thread-1",1)
thrad2 = myThread(2,"thread-1",2)

thrad1.start()
thrad2.start()

thrad1.join()
thrad2.join()

print("退出线程")

线程同步

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("开启线程:" + self.name)
        # 获取锁,用于线程同步
        threadLock.acquire()
        print_time(self.name,self.counter,3)
        # 释放锁,开启下一个线程
        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()
threas = []

# 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()

# 添加到线程列表
threas.append(thread1)
threas.append(thread2)

# 等待线程完成
for t in threas:
    t.join()

print("退出主线程")