We are in a situation that have a large application and now there is a situation that would need to know which .so module is allocating how much memory. I have no idea here, I was wondering a custom allocator overriding operator new, but that didn't help because I still cannot trace which module is doing to allocation. Replacing new by custom allocator would be terrible amount of work. Does anyone know how can I tell which module is doing how much allocations ?
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2 Answers
You could make use of the LD_PRELOAD trick to hook malloc, realloc, free etc. That, combined with the info gleaned from boost.stacktrace would get you most (if not all) of what you need. Not trivial though.
2 Comments
Martin Kosicky
that doesn't seem very performant. Is there a way how to preload malloc realloc for each .so module (some different function? )
G.M.
Not as far as I know. At the end f the day there's always going to be some performance hit -- you're intercepting calls to malloc etc. and doing extra work around the real call. As for exactly what that hit is and whether or not it's acceptable...? Only testing will tell.
It's not easy.
You can hook malloc, free, realloc globally in the application. Corresponding articles on Stackoverflow: How to use __malloc_hook?, An alternative for the deprecated __malloc_hook functionality of glibc.
You can retrieve a caller address from that hooks using __builtin_return_address and compare it with addresses of shared libraries. Maybe you have to examine a deeper frame address to get a proper address in a library, not an address of libc++. Read this Stackoverflow article __builtin_return_address returns null for index >0?.
