Shulou(Shulou.com)06/03 Report--

How to analyze Python3 object garbage collection mechanism, I believe that many inexperienced people are helpless about this, this article summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

Analysis of object garbage collection mechanism in Python 3

GC, as an automatic memory management mechanism for modern programming languages, focuses on two things: 1. Find useless garbage resources in memory 2. Clean up this garbage and free up memory for other objects to use. In Python, it keeps a counter in each object to keep track of the number of references to that object. Once this counter is 0, the object is immediately reclaimed and the memory space occupied by the object is freed.

reference count

We can use simple variable references and destructions to get a glimpse of the reference counting process.

Increase reference count

There are many ways to increase the reference count, that is, the object is referenced, then the counter will be +1

#Create the first reference a = 3 #Reference b = a with another variable name #Become a container object L = [1, a]#Pass str(a) as an argument

Decreasing reference count

Similarly, here are some ways to reduce the reference count

#A local reference has left its scope. For example `str()` str(a)#object alias is explicitly destroyed del a #object alias is copied to other objects a = 'Python'#object is removed from a window object L.remove(a)#window object itself is destroyed del L

Circular reference problem

What is circular reference? A and B refer to each other without any external references to either A or B, both of which have reference counts of 1, but obviously should be recycled.

#Reference count of object A is 1a = {}#Reference count of object B is 1b = {}#Reference count of object B is incremented by 1a ('b ')= b#Reference count of A is incremented by 1b ('a')= a#Reference of A is decremented by 1, reference of object A is 1del a#Reference of B is decremented by 1, reference of object B is 1del b

In this example, after the program executes the del statement, objects A and B have no references to these two objects, but these two objects still refer to this object, although the two objects have been del, that is, we can no longer use these two objects, namely garbage objects, but their reference count has not decreased to zero. That is, according to the reference-counting mechanism, they are not recycled and will remain in memory, causing memory leaks. In order to solve the circular reference problem of objects, Python introduces two GC mechanisms, mark-clean and generational collection, to solve this problem.

After reading the above, do you know how to analyze the object garbage collection mechanism in Python 3? If you still want to learn more skills or want to know more related content, welcome to pay attention to the industry information channel, thank you for reading!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.