mfunyu/malloc

Find out the workings behind optimum memory management and recode it, as well as free and realloc.

malloc

Use bonus compilation to enable all features

mandatory

compilation

make

usage

• can be run with any program compiled with libc
• for Linux

  LD_PRELOAD=./libft_malloc.so ./a.out
  

• for mac

  DYLD_INSERT_LIBRARIES=./libft_malloc.so DYLD_FORCE_FLAT_NAMESPACE=1 ./a.out
  

bonus

• show_alloc_mem_ex() function is available
• malloc debug environment variables are enabled
• freed memory is defragmented

! does not work with multi-threaded programs

compilation

make fclean
make bonus

environments

• types

  Name	Details
  MallocShowHeap	show detailed heap log and freelists at the end of the execution
  MallocShowAbbr	show abbriviated heap log and freelists at the end of the execution
  MallocShowFree	show freelists at the end of the execution
  MallocDebug	log each call to each malloc free realloc calloc function
  MallocHelp	show availiable environment variables and quick explanations

• usage

  • a. export environment variable

    export MallocShowHeap=1
    

  • b. without exporting (for Linux)

    MallocShowHeap=1 LD_PRELOAD=./libft_malloc.so LD_LIBRARY_PATH=. ./a.out
    

Tests

single tests

usage

• run

  ./test/run.sh [N]
  

• compare

  • result cannot be compared with original version if this message is shown

    > executable 'original' cannot be created for this test

  • the same test can be run with original malloc by ./original if this message is shown

    > executable 'original' created for compareson run

    ./original
    

• apply enviroment varialbes to a test without using export

  • compile

    make single_test FILENO=[N]
    

  • run

    MallocHelp=1 LD_PRELOAD=./libft_malloc.so LD_LIBRARY_PATH=. ./single_test
    

test details

Test no.	Name	Details
0	basic test	Nmallocs -> Nfrees : malloc multiple size in all size regions, and free them all at the end. Check most basic allocations.
1	basic test1	malloc -> free -> malloc : malloc the exact same size region just after the free of the same size chunk.
2	basic test2	malloc -> wirte -> read : malloc ereas and write and read from them to varify if it works.
3	tiny test	Nmalloc : malloc as much as possible with tiny allocation size.
4	small test	Nmalloc : malloc as much as possible with small allocation size.
5	large test	Nmalloc : malloc as much as possible with large allocation size.
6	basic realloc test	malloc -> realloc : realloc malloced ptr with different sizes and check there contents.
7	freelists test	mallocx2 -> free : malloc twice each time and free the first one to allow them to be stored in a freelist.

benchmark tests

• The library needs to be compiled with make bonus

./test/benchmark.sh

Google Test

• Google Test uses malloc, so replacing original malloc will cause problems to run the test

• Therefore, the test loads malloc as ft_malloc using dlopen

• To enable google testing, malloc and realloc function does not call malloc internally. It instead calls malloc_ function to avoid calling real malloc during testing.

• run (build)

  make gtest
  

• for bonus compilation

  • This will execute all tests in one process, allowing the tests of extended memory regions.

  make test