Заметил интересное поведение, понять которое не могу.
При импортировании модуля math кол-во ссылок на объект None уменьшается:
import sys
print(sys.getrefcount(None))
import math
print(sys.getrefcount(None))
Вывод:
4138
4099
Стало интересно, почему так происходит. Если кто объяснит буду рад)
Как сказали проффесионалы:
I think this is just the method cache filling up in Python 3.8. When a cache entry gets filled, it drops a reference to None and instead holds a reference to a string.
A little printf-debugging showed this:
>>> import math INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\listobject.c:2488 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\listobject.c:2488 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\compile.c:1331 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\compile.c:1331 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:6805 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:6805 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3390 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3391 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None INCREF None INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:6805 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3390 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3391 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\typeobject.c:3160 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:4971 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2978 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2979 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\frameobject.c:430 INCREF None INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2373 INCREF None INCREF None INCREF None INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3390 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3391 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:1363 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\weakrefobject.c:939 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Objects\funcobject.c:585 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3390 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:3391 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\ceval.c:2995 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Include\object.h:560 DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\pythonrun.c:268 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Modules\_io\bufferedio.c:804 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\pythonrun.c:1126 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Modules\_io\bufferedio.c:804 INCREF None DECREF None at C:\Users\sween\Source\Repos\cpython2\cpython\Python\pythonrun.c:1134
Перевод:
Я думаю, что это просто заполнения кэша методов в Python 3.8. Когда запись кэша заполняется, она удаляет ссылку на None и вместо этого содержит ссылку на строку.
Небольшой отладочный printf показал это:
-- обрезано --
То есть дело в том что math не хватает кэша методов (method cache) и он удаляет оттуда лишние None.
я конечно не знаток, но мне кажется что для math надо много памяти, а None самый ненужный оператор. попробуй создать функцию, после импорта math, и ссылки опять уменьшатся.
import sys
print(sys.getrefcount(None))
import math
print(sys.getrefcount(None))
def no():
pass
print(sys.getrefcount(None))