Reference counting
Python and various other programming languages employ reference counting, a memory management approach, to automatically manage memory by tracking how many times an object is referenced. A reference count, or the number of references that point to an object, is a property of each object in the Python language. When an object’s reference count reaches zero, it becomes un-referenceable and its memory can be freed up.
Examples :
Example 1: Simple Reference Counting
Python3
# Create an objectx = [1, 2, 3]# Increment reference county = x# Decrement reference county = None |
Example 2: Reference Counting with Cyclic Reference
Python3
# Create two objects that refer to each otherx = [1, 2, 3]y = [4, 5, 6]x.append(y)y.append(x) |
Example 3: Using the sys.getrefcount() function
Python3
import sys# Create an objectx = [1, 2, 3]# Get reference countref_count = sys.getrefcount(x)print("Reference count of x:", ref_count) |
Output :
Reference count of x: 2
Garbage Collection in Python
Python’s memory allocation and deallocation method is automatic. The user does not have to preallocate or deallocate memory similar to using dynamic memory allocation in languages such as C or C++.
Python uses two strategies for memory allocation:
- Reference counting
- Garbage collection
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