python之并发编程(线程进程协程) (2)

In CPython, the global interpreter lock, or GIL, is a mutex that prevents multiple native threads from executing Python bytecodes at once. This lock is necessary mainly because CPython’s memory management is not thread-safe. (However, since the GIL exists, other features have grown to depend on the guarantees that it enforces.)

 

上面的核心意思就是，无论你启多少个线程，你有多少个cpu, Python在执行的时候会在同一时刻只允许一个线程运行

 

二、<python的线程与threading模块> 1.线程的两种调用方式

threading 模块建立在thread 模块之上。thread模块以低级、原始的方式来处理和控制线程，而threading 模块通过对thread进行二次封装，提供了更方便的api来处理线程。

直接调用：

import threading import time def sayhi(num): #定义每个线程要运行的函数 print("running on number:%s" %num) time.sleep(3) if __name__ == '__main__': t1 = threading.Thread(target=sayhi,args=(1,)) #生成一个线程实例 t2 = threading.Thread(target=sayhi,args=(2,)) #生成另一个线程实例 t1.start() #启动线程 t2.start() #启动另一个线程 print(t1.getName()) #获取线程名 print(t2.getName())