Memory Allocation
samwho.dev
Memory Allocation
1–10 of 182 posts
Re: Memory Allocation
#2It even has a playground! https://samwho.dev/allocator-playground/
How I wish I had something like that when I first learned C.
Re: Memory Allocation
#3It even has a playground! https://samwho.dev/allocator-playground/ How I wish I had something like that when I first learned C.
The playground was the inspiration for the post. I always wanted to be able to fiddle with malloc implementations and see how they work in this way.
Admittedly the playground is hard to understand at first, and a touch janky in places. But the workloads are taken from for-real malloc/free traces on programs!
Re: Memory Allocation
#4It even has a playground! https://samwho.dev/allocator-playground/ How I wish I had something like that when I first learned C.
The playground was the inspiration for the post. I always wanted to be able to fiddle with malloc implementations and see how they work in this way. Admittedly the playground is hard to understand at first, and a touch janky in places. But the workloads are taken from for-real malloc/free traces on programs!
When you think that I (and probably the vast majority of developers) used a pen and a paper for the first few years every time I tried to visualize more complex memory, then that's a big upgrade.
Especially because you can scroll through all the steps.
Re: Memory Allocation
#5All credit goes to my wonderful friend Sam Who: https://twitter.com/samwhoo
He recently published a similar guide on load balancing that is equally intuitive and insightful: https://samwho.dev/load-balancing/
I can't wait to see what he puts out next!
Re: Memory Allocation
#6Ahh yes. Back at university we had a class called efficient programming where we had to implement a Unix utility and optimize it for speed, meaning cpu cycles.
While aggressively optimizing we replaced malloc in the end with a function we called "cooloc", that traded portability and security for speed. The debug tool here would have been useful.
Re: Memory Allocation
#7Thank you for this, this is helpful.
I wrote a JIT compiler and I didn't bother calling free much, I just let the operating system free up all allocated memory.
I got into this situation often:
return_struct = do_something(mystruct);
return_struct->inner_struct = malloc(sizeof(struct my_inner_struct));
I feel this ownership complicates cross-language FFI API calls, because who is responsible for freeing structures depends on the application and the platform you're running under. For example, Rust code being called from Erlang. You have to be extra careful when memory is managed by a different language runtime.
I feel I am at the beginning of intuitively understanding what memory really is: memory is just a huge contiguous region of numbered locations. Bump allocators allocate in one direction and free all at once. Arena allocators allocate to a preallocated region, I think.
Memory is a logistical problem of how you arrange and allocate finite resources.
I am thinking of alternative visualizations of understanding memory, for example, I started writing an animation of binary search:
https://replit.com/@Chronological/ProgrammingRTS
The idea is that you see values and memory locations move around with the final goal being able to command memory to move around and be computed, such as real time strategy game.
I think if we could visualise memory as cars on a road, we would see obvious traffic jams.
Re: Memory Allocation
#8This is absolute gold. When I use things like this, I am reminded how powerful digital learning can be. So much more capable then just text or video. But very little content is this well put together. Probably because it is so time intensive.
Re: Memory Allocation
#9This is absolute gold. When I use things like this, I am reminded how powerful digital learning can be. So much more capable then just text or video. But very little content is this well put together. Probably because it is so time intensive.
This feedback has made my day. Thank you.
I'm inspired by Bartosz Ciechanowski and Julia Evans. The web is such a powerful toolbox. So many concepts are more complex than text alone can hope to explain. Those two are so creative and full of energy.
And you're right, it's incredibly time intensive to put these together. Thousands of lines of code, plus the text content, plus reaching out to domain experts for reviews (shout out Chris Down, kernel wizard extraordinaire).
Re: Memory Allocation
#10Love this. It is so important to know these fundamentals concepts. I would like to see a similar version for SQL database indexes as 99% of the engineers I work with have no idea how to use them.