Python的内存管理

# -*- coding: utf-8 -*-

# 对象与引用
# 1为对象，a是一个引用，引用a指向对象1
a = 1

# 创建多个等于1的引用
b = 1

if __name__ == '__main__':
    # 打印对象的内存地址
    print id(a)
    print hex(id(a))
    
    # 整数和短小的字符，python会缓存这些对象，以便重复使用
    print id(b)
    
    # 用is判断两个引用所指向的对象是否相同
    print (a is b)
    x = 'hello'
    y = 'hello'
    print (x is y)
    print (a is x)
    m = 'very good morning abcdefghijkl'
    n = 'very good morning abcdefghijkl'
    print (m is n)
    
    # 查看对象的引用计数
    from sys import getrefcount
    a = [1, 2, 3]
    print getrefcount(a)
    b = a
    print getrefcount(b)
    
    # 
    import gc
    gc.collect()
    print gc.get_threshold()
    
    ####
    a = []
    b = [a]
    a.append(b)
    print getrefcount(a)
    print getrefcount(b)
    del a
    del b
    
    x = [1, 2, 3]
    y = [x, dict(key1=x)]
    z = [y, (x, y)]
    import objgraph
    objgraph.show_refs([z], filename='ref_topo.png')

参考：http://www.cnblogs.com/vamei/p/3232088.html