You can read my Substack post that I wrote about this project.
This project was done solely for educational purposes. It is by no means intended for use in a production environment.
This project is a custom implementation of the C family of functions in charge of dynamic memory management: malloc, calloc, realloc and free.
Each managed block carries metadata ahead of the allocated memory. There is also a footer after the allocated space to store a duplicate of the block's size. This information is used to let the program access a block's header from the next block in memory.
Free memory blocks are kept in buckets, according to a mapping from block size to bucket. Inside each bucket, free memory blocks are kept sorted in ascending size order, to help perform a best-fit search when a free block is requested by the client.
Those are only the broad lines of my implementation. However, I have extensively documented my code with comments. Therefore, by reading src/malloc.c, you should be able to get all the details of the implementation.
A simple benchmark comparing the custom functions with the built-in functions is provided.
To run the benchmark, first run make from the project's root directory. Then, run the my_malloc executable file.
The main danger that I see with this implementation is the lack of error detection. More precisely, no checks are made to ensure that header and footer metadata were unaltered during client use. Corruption of this metadata will break the program. A way of dealing with this would be to include some sort of checksum verification.
Also, blocks under management by this implementation have a minimum size of 32 bytes. In a program where the client only ever needs very small blocks, i.e., blocks of 16 bytes (to store two pointers on a system with 8-byte pointers), memory allocation will suffer a 100% overhead.
Even though I had to conduct a fair deal of research to build this project, I still by no means consider myself to be an expert – or even a knowledgeable person – in dynamic memory management.
Consequently, I am convinced that there are many more downsides and shortcomings that I fail to identify at this time.