Memory Management in Python | Python Notes | Digital Community

What About Single Reference And Multiple Objects?

 

Before reading these notes first you have to see Lecture-14 video. So that you can easily understand what is written below.

So from 2 lectures, We are regularly discussing that if we have a single reference and what if we create multiple objects.

So let’s discuss it with an example

        a=10

        a=20

        a=30

 

So when the above 3 lines will run then Python creates 3 objects one by one and the variable a starts pointing 30

So let’s understand with a diagram

 

 

 

This arises a question that what will happen with the other objects whose values are 20 and 30

So before understanding what will happen to the other objects we have to understand 3 important terminologies.

 

1.      1. Reference Counting

2.      2. Garbage Block

3.     3. The Garbage Collector

 Let’s understand all the terminologies one by one.

 First, we’ll talk about Reference Counting.

So let’s understand it with an example.

        a=10

        b=10

 

Let’s understand with a diagram that by writing these lines what happens in the memory.

So here we can see that a and b both the references were pointing the same object this means the reference count of the object will be 2.

REFERENCE COUNT – Reference count is a number which tells the interpreter that the object was pointed by how many references.

Then we will write b=20

Let’s see  the effect

So the address of  the object who is pointing 20 is stored in both the references a and b and the object who is pointing 10 whose reference count now becomes 0.

 

So, The object block whose reference count is zero and no one is referring to the object this object block is known as the Garbage block.

 

As we see in the diagram that no one is referring to the objects which is pointing to 10 this object is now a garbage block.

Until then we saw that what is reference counting and to whom do we call garbage block.

Now what after this, we already understood what is the reference counting and garbage block. So what after this?

So Now comes Garbage Collector

The Garbage collector always keeps a round of memory as every morning the vehicle of Municipal Corporation has come in your house and collect the garbage from your house, Same work is with your garbage collector this always keeps a round of memory and if it sees any object which is not referenced by any reference then it collects that object and clears the memory. And this is called a Garbage collector in Python.

 

 

So as we see in our example that the object whose value is 10 is now not referencing by any reference. So this object is now removed by Garbage collector and our memory is free now.

So this is the way in Python for memory management.

 

Now we will talk about their advantages and disadvantages.

So the main advantage of this approach is that the unused memory is clear now and we programmers are able to re-use the memory.

But the disadvantage of this approach is that our garbage collector will have to check regularly that any object’s reference count is zero or not. And this is one of the reasons why Python is slower than other languages.

 But again this process happens very faster and it doesn’t matter to us but yes if we compare with other languages it is slow a little bit.

I hope that you must have understood this how Python manages memory and in what way.

Even after that if you have any doubt then you will ask your questions on the comment section and I will try to reply you as soon as possible.

 

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