我有我的代碼中使用了很多小的方便類如下:循環引用的對象沒有得到垃圾收集
class Structure(dict):
def __init__(self, **kwargs):
dict.__init__(self, **kwargs)
self.__dict__ = self
關於它的好處是,你可以通過訪問屬性字典的鍵語法或通常對象樣式:
myStructure = Structure(name="My Structure")
print myStructure["name"]
print myStructure.name
今天,我已經注意到,我的應用程序的內存消耗是在我本來期望它減少的情況略有增加。在我看來,從結構類生成的實例不垃圾收集。在這裏說明這是一個小片段:
import gc
class Structure(dict):
def __init__(self, **kwargs):
dict.__init__(self, **kwargs)
self.__dict__ = self
structures = [Structure(name="__{0}".format(str(value))) for value in range(4096)]
print "Structure name: ", structures[16].name
print "Structure name: ", structures[16]["name"]
del structures
gc.collect()
print "Structures count: ", len([obj for obj in gc.get_objects() if type(obj) is Structure])
用下面的輸出:
Structure name: __16
Structure name: __16
Structures count: 4096
當你注意到結構實例數仍是4096
我評論的行創建方便的自我參考:
import gc
class Structure(dict):
def __init__(self, **kwargs):
dict.__init__(self, **kwargs)
# self.__dict__ = self
structures = [Structure(name="__{0}".format(str(value))) for value in range(4096)]
# print "Structure name: ", structures[16].name
print "Structure name: ", structures[16]["name"]
del structures
gc.collect()
print "Structures count: ", len([obj for obj in gc.get_objects() if type(obj) is Structure])
既然循環引用被移除時輸出有意義:
Structure name: __16
Structures count: 0
我推一點進一步使用Melia分析內存消耗測試:
import gc
import pprint
from meliae import scanner
from meliae import loader
class Structure(dict):
def __init__(self, **kwargs):
dict.__init__(self, **kwargs)
self.__dict__ = self
structures = [Structure(name="__{0}".format(str(value))) for value in range(4096)]
print "Structure name: ", structures[16].name
print "Structure name: ", structures[16]["name"]
del structures
gc.collect()
print "Structures count: ", len([obj for obj in gc.get_objects() if type(obj) is Structure])
scanner.dump_all_objects("Test_001.json")
om = loader.load("Test_001.json")
summary = om.summarize()
print summary
structures = om.get_all("Structure")
if structures:
pprint.pprint(structures[0].c)
產生以下輸出:
Structure name: __16
Structure name: __16
Structures count: 4096
loading... line 5001, 5002 objs, 0.6/ 1.8 MiB read in 0.2s
loading... line 10002, 10003 objs, 1.1/ 1.8 MiB read in 0.3s
loading... line 15003, 15004 objs, 1.7/ 1.8 MiB read in 0.5s
loaded line 16405, 16406 objs, 1.8/ 1.8 MiB read in 0.5s
checked 1/ 16406 collapsed 0
checked 16405/ 16406 collapsed 157
compute parents 0/ 16249
compute parents 16248/ 16249
set parents 16248/ 16249
collapsed in 0.2s
Total 16249 objects, 58 types, Total size = 3.2MiB (3306183 bytes)
Index Count % Size % Cum Max Kind
0 4096 25 1212416 36 36 296 Structure
1 390 2 536976 16 52 49432 dict
2 5135 31 417550 12 65 12479 str
3 82 0 290976 8 74 12624 module
4 235 1 212440 6 80 904 type
5 947 5 121216 3 84 128 code
6 1008 6 120960 3 88 120 function
7 1048 6 83840 2 90 80 wrapper_descriptor
8 654 4 47088 1 92 72 builtin_function_or_method
9 562 3 40464 1 93 72 method_descriptor
10 517 3 37008 1 94 216 tuple
11 139 0 35832 1 95 2280 set
12 351 2 30888 0 96 88 weakref
13 186 1 23200 0 97 1664 list
14 63 0 21672 0 97 344 WeakSet
15 21 0 18984 0 98 904 ABCMeta
16 197 1 14184 0 98 72 member_descriptor
17 188 1 13536 0 99 72 getset_descriptor
18 284 1 6816 0 99 24 int
19 14 0 5296 0 99 2280 frozenset
[Structure(4312707312 296B 2refs 2par),
type(4298634592 904B 4refs 100par 'Structure')]
內存使用量爲3.2MiB,刪除自引用行會導致以下輸出:
Structure name: __16
Structures count: 0
loading... line 5001, 5002 objs, 0.6/ 1.4 MiB read in 0.1s
loading... line 10002, 10003 objs, 1.1/ 1.4 MiB read in 0.3s
loaded line 12308, 12309 objs, 1.4/ 1.4 MiB read in 0.4s
checked 12/ 12309 collapsed 0
checked 12308/ 12309 collapsed 157
compute parents 0/ 12152
compute parents 12151/ 12152
set parents 12151/ 12152
collapsed in 0.1s
Total 12152 objects, 57 types, Total size = 2.0MiB (2093714 bytes)
Index Count % Size % Cum Max Kind
0 390 3 536976 25 25 49432 dict
1 5134 42 417497 19 45 12479 str
2 82 0 290976 13 59 12624 module
3 235 1 212440 10 69 904 type
4 947 7 121216 5 75 128 code
5 1008 8 120960 5 81 120 function
6 1048 8 83840 4 85 80 wrapper_descriptor
7 654 5 47088 2 87 72 builtin_function_or_method
8 562 4 40464 1 89 72 method_descriptor
9 517 4 37008 1 91 216 tuple
10 139 1 35832 1 92 2280 set
11 351 2 30888 1 94 88 weakref
12 186 1 23200 1 95 1664 list
13 63 0 21672 1 96 344 WeakSet
14 21 0 18984 0 97 904 ABCMeta
15 197 1 14184 0 98 72 member_descriptor
16 188 1 13536 0 98 72 getset_descriptor
17 284 2 6816 0 99 24 int
18 14 0 5296 0 99 2280 frozenset
19 22 0 2288 0 99 104 classobj
確認結構情況下已被銷燬和內存使用率降至2.0MiB。
任何想法我怎麼能確保這個類得到正確的垃圾收集?順便說一下,所有這些都是在Python 2.7.2(Darwin)上執行的。
乾杯,
托馬斯
你爲什麼要這樣的自我引用?即使你堅持屬性訪問和項目查找的雙重性(恕我直言,根據Python的Zen),還有更好,更簡單的方法來實現這一點。 – delnan 2011-12-31 11:53:14