Utilities developed to measure memory usage in projects with mixed Rust/C++ code while having minimizing performance/memory overhead.

Goals

• Track memory usage/leaks in large Rust projects, where memory leak could potencially practially everywhere: for example: application itself, any of hundreds imported Rust libraries or even with liked C/C++ code.
• Low performance overhead - existing tools like Valdrid can slow down program by a factor of 25-50 times, using such approach would be impractical.
• Low memory overhead - Adds extra 32 bytes per each memory allocation on heap. While it's easy to add extra memory to a machine when needed, adding extra CPU cores will not help with applications limited by a single core performance. This can be optimized if needed by either reducing header size or by doing random sampling for small allocations.
• Ability to dump memory while process is running without affecting it.

Requirements

• Linux operating system - dump script uses linux proc filesystem to read process information. This can be extended to other platform if needed in the future.

Design

Rust allocator proxy: Tracking Rust allocation is done by adding a proxy, which uses jemalloc and add 32 bytes header to all allocations. See https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html

C allocator proxy: Tracking C allocator is done in by overriding dynamic links to malloc/free/etc. This can be overriden by providing an enviroment variable while running an executable `LD_PRELOAD=./mtrace.so path'.

dump script:

• Reads process memory mapping from /proc/<PID>/smaps.
• It's able to identify which pages are present by reading from /proc/<PID>/pagemap.
• It reads memory using /proc/<PID>/pagemap
• Once memory is read, regions of memory allocated by Rust/C code can be identified by looking for MAGIC keyword, which is part of the header.

The core tool is in dump.cpp file. It dumps the program memory and it prints memory statistics.

Modules

• near-rust-allocator-proxy inside near-rust-allocator-proxy folder
• near-c-allocator-proxy near-c-allocator-proxy.c inside near-dump-analyzer folder.
• near-dump-analyzer dump.cpp inside near-dump-analyzer folder