I have C Linux application which continuously allocates and frees memory (around 200 alloc/free per sec) using malloc, calloc, realloc & free functions. Even though all allocated memory are freed (verified by wrapping *alloc and free), the VmSize, VmRSS & VmData numbers are keep on increasing and finally application is getting killed by OOM killer.
Why the VmSize, VmRSS & VmData are keep on increasing? if it is Memory management issue, any pointers to avoid this?
I saw this Problem usage memory in C, but the answers are not explaining the OOM behavior.
You should first use valgrind (to debug potential hard to find memory leaks or misbehavior). Don't forget to compile with gcc -Wall -g (then, when it works, use -Wall -O); of course, improve your code till no warnings are given.
You could probably (if the algorithms fit) try to (usefully) allocate memory zone of e.g. either power of two, or 3 times a power of two [perhaps minus 2 or 3 words]; at least try to avoid too many different random sizes of allocation.
You may want to try using Boehm's conservative garbage collector - i.e. replacing all your malloc with GC_MALLOC (or GC_MALLOC_ATOMIC & strdupwith GC_STRDUP), your free with GC_FREE, etc...
At least for testing purposes, use setrlimit(2) perhaps thru the bash ulimit builtin. You want RLIMIT_AS - possibly with RLIMIT_DATA (setting these limits sensibly avoids the OOM killer and makes your mmap -called by malloc- fail when memory is exhausted).
You may want to compile with GCC 4.8 which accepts -fsanitize=address.
You could also implement your own application specific garbage collector (read that wikipage, it gives you insights and terminology); a mark & compact algorithm will fight fragmentation.
See also this question about memory fragmentation. Look into the Plug tool.
