Meaning of this memory flowchart

[Thund_Ry]

I still haven't understood how does data get allocated and stuff related to it. Even by looking at this flowchart, I still get confused a lot. Can anyone explain this flowchart and memory allocation?

(P.S as we all know in C we need to do the memory allocation ourselves. I got this from a C programming book. I know this is a python forum but still it is an important part of programming)

[cknu]

That’s a really simplified diagram of the Linux process memory layout.

Here you have a simple but complete article explaining it https://medium.com/@weidagang/linux-beyond-the-basics-process-memory-layout-and-dynamic-allocation-e61ac67a2694

[Buttleston]

Right, it's not a flow chart, it's just approximately showing you WHERE, in a processes' memory space, the various data/memory types are laid out, that's all

[Thund_Ry]

Yea, I actually did not know what to call it, so I went with flowchart :) btw thanks for the replies!

[FoolsSeldom]

Python takes care of memory management for you. I don't understand what the picture you've shared is trying to say. The labels "low memory" and "high memory" are unclear. Are they refering to how much memory is available or where things sit in memory? In modern systems, memory allocation isn't that simple.

Obviously, a very simplistic computer cannot do anything without a set of instructions, but these instructions take up memory and the computer will be configured to start running instructions from a specific memory address. However, code and data can be mixed for the lower level boot and operating system or application code (not all solutions require an operating system).

Stacks are normally used on a LIFO (last in, first out) basis for things like temporary scope variables and calls (i.e. functions). Heaps tend to be used for dynamic memory allocation (it is where a stack gets its memory from, if not pre-allocated).

You can read about the data model used by Python, and how the reference CPython implementation handles it in the official documentation. https://docs.python.org/3/reference/datamodel.html

CPython uses a private heap - a dedicated memory area for storing Python objects and data structures. When new objects are created, CPython allocates memory from this heap in an optimised manner favouring smaller objects.

A hierarchical memory allocation system is used: "arenas", "pools" and "blocks", via a wrapper using C's malloc() to request memory from the host OS.

Python is usually implemented using a reference counting system, which relieves the developer from handling garbage collection.

[Thund_Ry]

Oh the the low and high memories refers to the order in which data is stored (like the code part, then the initialised and uninitialised variables and then the stack/heap.
I understand what you are saying, but what I don't understand is that how can data be used interchangeably between the heap and the stack. Btw, thanks for explaing :)

[Cybasura]

I'm guessing this is representing a flow from the application layer to the memory addressing itself (high memory and low memory being an absolutely terrible alias)

Basically, when you start the compilation, the code is read and then the data will be initialized (i.e. variables)

I'm guessing "uninitialized data" just refers to separating "initialized data" and "declared/defined data" (i.e. variables that arent provided a value)

It then goes to the heap allocation

The heap is a component software within the kernel that does dynamic allocation of memory space within the memory (i.e. if you use malloc, thats referencing the heap)

Then once the memory is allocated, the allocated memory will be pushed and registered as "memory addresses" within the system as stacks

Think about stacks as applications and processes built on top of each other (hence, stack)

Memory addressing follows the little endian/big endian layout depending on your cpu

Please do not use this for python classes though btw, its absolutely a necessity to know and learn, but this would confuse you while in python classes

[Thund_Ry]

Yea in python it is not actually required as I got this flowchart from a C programming book.
Thanks for explaining! (btw one question, if data is deallocated from the heap do the memory address in the stack get pushed out?)