Memory allocation in OCaml and beyond

In this video I look into how memory allocation works in OCaml 4, how it is different from OCaml 5 (aka multi-core). I browse the source-code of OCaml runtime and do a bunch of experiments to demonstrate the behaviour of the allocator depending on the size of allocated objects. Finally, I show how the allocator behaviour on MacOS is different from that on Linux with an extra sprinkle of C++.

Contents:
00:00 Intro
00:21 Context - Infer
01:11 Context - OCaml
02:19 Multi-core OCaml
03:11 Context - increased memory consumption with OCaml 5
04:23 Plan for the video
05:06 Memory allocation behaviour in OCaml 4
06:54 Memory allocation behaviour with OCaml 5
08:10 Disclaimer
08:41 Exploring OCaml 4 memory allocation
10:07 OCaml 4: allocating on minor vs major heaps
11:10 OCaml 4: continuing with the major heap allocation
12:18 Note on mmap vs malloc
13:51 OCaml 4: allocate + strace
14:39 glibc memory allocator
16:03 OCaml 5 and GC compaction patch
16:33 OCaml 5 memory allocation code
17:57 OCaml 5: pool vs large allocations on shared heap
20:02 OCaml 5: mmap vs malloc threshold
21:05 Setting up an opam switch with a custom OCaml compiler
23:01 Segfault happens
25:29 Running on MacOS... and nothing makes sense anymore
28:25 Dissecting the weirdness
29:36 C++ to rescue
31:24 MacOS memory under pressure
36:25 Outro

[snatvb]

my name is Артём 😁
u have nice english and thanks for the video

[kallekula]

This was super interesting as Im in the process pf learning OCaml!

[johncartergonzalez]

Awesome video! Quick, very important, question what emacs color scheme is that?