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This article mainly introduces how python uses _ _ slots__ to reduce memory expenses, which has a certain reference value. Interested friends can refer to it. I hope you can learn a lot after reading this article.

Use _ _ slots__ to reduce memory overhead

Have you noticed that your Python application takes up a lot of resources, especially memory? One trick is to use the _ _ slots__ class variable to reduce memory expenditure to some extent.

Import sysclassFileSystem (object): def _ init__ (self,files,folders,devices): self.files= filesself.folders= foldersself.devices= devicesprint (sys.getsizeof (FileSystem)) classFileSystem1 (object): _ _ slots__= ['files','folders','devices'] def _ init__ (self,files,folders,devices): self.files= filesself.folders= foldersself.devices= devicesprint (sys.getsizeof (FileSystem1)) # In Python 3.531-> 1016room2-> 888

Obviously, you can see from the results that there are savings in memory usage, but you should only use _ _ slots__ when the memory overhead of a class is unnecessarily large. Use it only after performance analysis of the application, otherwise you just make the code difficult to change without real benefits.

[translator's note: the above result in my win10 python2.7 is:

# In Python 2.7win10#1- > 896 win10#1--> 1016

Therefore, this comparison method is not so convincing. _ _ slots__ is mainly used to limit the attribute information of objects. In addition, it may cost less when there are many objects generated. For more information, please see the official documentation of python:

The slots declaration takes a sequence of instance variables and reserves just enough space in each instance to hold a value for each variable. Space is saved because dict is not created for each instance. ]

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