Hi all, 

I am trying to replace the version of malloc/free...etc with my own function suit. I am have issues with loading the initial library setup. 

I am looking for wisdom from the community as to why this may be the case.

Facts:
- i just grabbed the latest cpython repo
- my memory suit seem to be working from independent testing on other code
- i am working on linux
- i went into obmalloc.c and replaced the malloc, free, realloc, calloc with my own functions. 
- i changed the mmap/unmap to use my malloc and free in obmalloc.c
- my allocated produces aligned allocations.
- i dump the exceptions text being generated to see what is happening:
EXCEPTION:: module 'sys' has no attribute '__file__'
EXCEPTION:: type object 'BuiltinImporter' has no attribute '_ORIGIN'
EXCEPTION:: module 'sys' has no attribute '__cached__'
EXCEPTION:: module 'sys' has no attribute '__path__'
EXCEPTION:: module 'builtins' has no attribute '__file__'
EXCEPTION:: type object 'BuiltinImporter' has no attribute '_ORIGIN'
EXCEPTION:: module 'builtins' has no attribute '__cached__'
EXCEPTION:: module 'builtins' has no attribute '__path__'
EXCEPTION:: module '_frozen_importlib' has no attribute '__file__'
EXCEPTION:: type object 'FrozenImporter' has no attribute '_ORIGIN'
EXCEPTION:: module '_frozen_importlib' has no attribute '__cached__'
EXCEPTION:: module '_frozen_importlib' has no attribute '__path__'
EXCEPTION:: module '_imp' has no attribute '__file__'
EXCEPTION:: type object 'BuiltinImporter' has no attribute '_ORIGIN'
EXCEPTION:: module '_imp' has no attribute '__cached__'
EXCEPTION:: module '_imp' has no attribute '__path__'
EXCEPTION:: name '_bootstrap' is not defined
EXCEPTION:: name '_bootstrap' is not defined
EXCEPTION:: name '_bootstrap' is not defined
EXCEPTION:: name '_bootstrap' is not defined
Fatal Python error: initfsencoding: failed to get the Python codec of the filesystem encoding
Traceback (most recent call last):
  File "/home/paul/fresh_cpython/debug/../Lib/encodings/__init__.py", line 31, in <module>
  File "<frozen importlib._bootstrap>", line 989, in _find_and_load
  File "<frozen importlib._bootstrap>", line 973, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 773, in exec_module
  File "<frozen importlib._bootstrap_external>", line 909, in get_code
  File "<frozen importlib._bootstrap_external>", line 966, in get_data
OSError: [Errno 14] Bad address
Aborted

I suspect that this _bootstrap library is not being loaded correctly, and i can only assume that this is somehow because of my memory suit, but i am not really sure where to start hunting, as there is a lot of code. 

My goal is just to replace malloc. If there is a better way or i am making some wrong assumption, please let me know. 

Best, 
Paul

You have the issue with your functions, not with Python. Are you sure you do not have an issue with your code?

Hi @paul,

have you already checked https://docs.python.org/3/c-api/memory.html#customize-memory-allocators ?

Hi guys, 

First, thanks for the prompt replies. 

@matrixise: If there is i can't find it, but i am happy to accept it as a possibility. Equally, maybe there is an assumption about memory in the cpython implementation somewhere that goes against my memory allocator -> this is obviously not cpythons fault. The point of this 'issue' is to ask the community to suggest how i can go about finding where the problem is. As i said, there is a lot of code :)

@pablogsal: Yeah. I had a look in there. In cpython, i have made all allocations from obmalloc use my memory allocation functions, including the arenas. 

Perhaps a starting point would be if anyone has ideas about how to go about debugging this??

best, 

Paul

> The point of this 'issue' is to ask the community to suggest how i can go about finding where the problem is. As I said, there is a lot of code :)

Sadly, this tracker is to track bugs related to CPython. Modifying the interpreter to change the memory allocation scheme (replacing the code in obmalloc.c) is not supported, so I have to close this issue :(

You can try to ask the question on some of the mailing lists (like python-dev) to see is someone can help you with this. I would advice to also provide some minimal reproducer/example code, as is very difficult to recommend anything without knowing what exactly are you modifying.

If you think there is something wrong/we can improve around this area, please, feel free to reopen this issue or open a new one :)