垃圾回收

import sys #调用计数模块
import psutil
import os
import gc #垃圾回收模块
print(gc.get_threshold())#gc垃圾回收阈值
def showMenSize(tag):
pid=os.getpid()
p=psutil.Process(pid)
info=p.memory_full_info()
memory=info.uss/1024/1024
print(’{} memory used:{} MB’.format(tag,memory))
pass
#验证循环引用的情况
def func():
showMenSize(‘初始化’)
a=[i for i in range(1000000)]
b=[i for i in range(1000000)]
a.append(b)
b.append(a)
showMenSize(‘创建列表对象 a b 之后’)
# print(sys.getrefcount(a))
# print(sys.getrefcount(b))
# del a
# del b
pass
func()
gc.collect()#手动释放
showMenSize(‘完成时候的’)

# sys.getrefcount()

a=[]

print(sys.getrefcount(a))#两次

b=a

print(sys.getrefcount(a))#三次