# 使用方法
# 声明调用调试器：
import pdb
pdb.set_trace()

# 运行时，可通过执行下述指令查看程序中前20个最普遍的对象：
(pdb) import objgraph
(pdb) objgraph.show_most_common_types()

MyBigFatObject             20000
tuple                      16938
function                   4310
dict                       2790
wrapper_descriptor         1181
builtin_function_or_method 934
weakref                    764
list                       634
method_descriptor          507
getset_descriptor          451
type                       439

# 也可以查看两个时间点之间那些对象已经被添加或删除
(pdb) import objgraph
(pdb) objgraph.show_growth()


(pdb) objgraph.show_growth()   # this only shows objects that has been added or deleted since last show_growth() call

traceback                4        +2
KeyboardInterrupt        1        +1
frame                   24        +1
list                   667        +1
tuple                16969        +1

# 可以查看哪里包含给定对象的引用。
x = [1,2,3,4,5,6]
y = [x, [x], {"a":x}]
import pdb; pdb.set_trace()

# 想查看程序对变量x的引用，执行objgraph.show_backref()函数：
(pdb) import objgraph
(pdb) objgraph.show_backref([x], filename="x_mem.png")