CODEWITHSUNDEEP
pythongarbage-collection
Hailiang Zhang
Hailiang Zhang

Reputation: 18910

Why does sys.getrefcount() return 2?

As I understand, sys.getrefcount() returns the number of references of an object, which "should" be 1 in the following case:

import sys,numpy
a = numpy.array([1.2,3.4])
print sys.getrefcount(a)

However, it turned out to be 2! So, if I:

del a

Will the "numpy.array([1.2,3.4])" object still be there (no garbage collection)?

Upvotes: 29

Views: 11109

Answers (2)

Aman Gaur
Aman Gaur

Reputation: 1

Because of "self" variable which is compulsory be present in constructor of class. Self is also a reference variable.

Upvotes: -1

NPE
NPE

Reputation: 500585

When you call getrefcount(), the reference is copied by value into the function's argument, temporarily bumping up the object's reference count. This is where the second reference comes from.

This is explained in the documentation:

The count returned is generally one higher than you might expect, because it includes the (temporary) reference as an argument to getrefcount().

As to your second question:

If I "del a", will the "numpy.array([1.2,3.4])" object still be there (no garbage collection)?

By the time getrefcount() exits, the array's reference count will to back to 1, and a subsequent del a would release the memory.

Upvotes: 43

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