并发：指的是任务数多余cpu核数，通过操作系统的各种任务调度算法，实现用多个任务“一起”执行（实际上总有一些任务不在执行，因为切换任务的速度相当快，看上去一起执行而已）
并行：指的是任务数小于等于cpu核数，即任务真的是一起执行的
python的thread模块是比较底层的模块，python的threading模块是对thread做了一些包装的，可以更加方便的被使用
import time import threading def dancing(): for i in range(1, 4): print(‘跳舞中%d‘ % i) time.sleep(0.5) print(‘dancing 线程结束‘) def singing(): for i in range(1, 5): print(‘唱歌中%d‘ % i) time.sleep(0.5) print(‘singing 线程结束‘) def main(): # 创建子线程对象 t1 = threading.Thread(target=dancing) t2 = threading.Thread(target=singing) # 子线程开始执行 t1.start() t2.start() # 查看正在运行的子线程数量 while True: length = len(threading.enumerate()) print(‘当前运行的线程数为：%d‘ % length) if length <= 1: break time.sleep(0.2) if __name__ == ‘__main__‘: main()
import threading import time class DancingThread(threading.Thread): def run(self): for i in range(1, 3): print(‘线程名：%s，正在跳舞：。。。%d‘ % (self.name, i)) time.sleep(0.5) print(‘\n跳舞线程结束‘) class SingingThread(threading.Thread): def run(self): for i in range(1, 5): print(‘线程名：%s，正在唱歌：。。。%d‘ % (self.name, i)) time.sleep(0.5) print(‘唱歌线程结束‘) def main(): # 创建Thread对象 dancing = DancingThread() sing = SingingThread() # 调用run方法，开启线程 dancing.start() sing.start() if __name__ == ‘__main__‘: main()
import threading import time g_num = 0 class DancingThread(threading.Thread): def __init__(self, num): threading.Thread.__init__(self) self.num = num def run(self): global g_num for i in range(self.num): g_num += 1 print(‘跳舞线程结束，g_num：%d‘ % g_num) class SingingThread(threading.Thread): def __init__(self, num): threading.Thread.__init__(self) self.num = num def run(self): global g_num for i in range(self.num): g_num += 1 print(‘唱歌线程结束，g_num：%d‘ % g_num) def main(): # 创建Thread对象 dancing = DancingThread(1000000) sing = SingingThread(1000000) # 调用run方法，开启线程 print(‘初始g_num: %d‘ % g_num) dancing.start() sing.start() # 等待子线程运行完 while len(threading.enumerate()) > 1: time.sleep(1) print(‘线程结束后g_num: %d‘ % g_num) if __name__ == ‘__main__‘: main()
运行结果为：
初始g_num: 0 跳舞线程结束，g_num：1292807 唱歌线程结束，g_num：1712212 线程结束后g_num: 1712212
# 创建锁 mutex = threading.Lock() # 锁定 mutex.acquire() # 释放 mutex.release()
import time import threading g_num = 0 def dancing(num, mutex): global g_num for i in range(num): # 上锁 mutex.acquire() # 计算 g_num += num # 解锁 mutex.release() print(‘dancing 线程结束,num值： %d‘ % g_num) def singing(num, mutex): global g_num for i in range(num): # 上锁 mutex.acquire() # 计算 g_num += num # 解锁 mutex.release() print(‘dancing 线程结束,num值： %d‘ % g_num) def main(): print(‘初始值：%d‘ % g_num) # 创建锁对象 mutex = threading.Lock() # 创建子线程对象 t1 = threading.Thread(target=dancing, args=(1000000, mutex, )) t2 = threading.Thread(target=singing, args=(1000000, mutex, )) # 子线程开始执行 t1.start() t2.start() if __name__ == ‘__main__‘: main()
运行结果：
初始值：0 dancing 线程结束,num值： 1876392000000 dancing 线程结束,num值： 2000000000000
原文：https://www.cnblogs.com/gcxblogs/p/12930887.html