Malldump

Attach to a process and dump statistics of low level malloc(ptmalloc, the glibc implementation) of the process.

Supported malloc implementations

• ptmalloc, also known as ptmalloc2

Supported platforms

• Linux

Supported architectures

• x86_64
• aarch64
• arm

Build

mkdir build && cd build
cmake .. && make

Usage

usage:
  -h           print this usage
  -D           debug mode [defaut: false]
  -t <arg>     type of malloc [default: ptmalloc]
  -p <arg>     pid of the target process
  -I <arg>     offset of mallinfo [default: ...]
  -P <arg>     offset of mp_ [default: ...]
  -A <arg>     offset of narenas [default: ...]
  -H           display size of memory in human mode [default: false]

malldump -H -p <pid>

Outputs

Process cmd:    nmap -sP 172.17.0.0/16
Process pid:    49457
Threads:        1
Arenas:         1
Total memory:   10248.0K
Avail memory:   403.1K
Used memory:    9844.9K
Used memory%:   96.07%
Free chunks:    2
Fastbin chunks: 3
Fastbin memory: 0.2K
Mmapped chunks: 1
Mmapped memory: 516.0K
Trim threshold: 128.0K
Mmap threshold: 128.0K
Arena max:      16

• Arenas: Number of created arenas.
• Total memory: Total memory that allocated from OS through brk() or mmap().
• Avail memory: Memory that kept by low level malloc but not used by application.
• Used memory: Memory that used by application through malloc().
• Used memory%: used memory / total memory.
• Free chunks: Chunks that linked in the double-linked list of bins except fastbins.
• Fastbin chunks: Chunks that linked in the single-linked list of fastbins.
• Mmapped chunks: Chunks that allocated from OS directly by mmap().
• Mmapped memory: Total memory of mmapped chunks.
• Trim threshold: The maximum amount of unused top-most memory to keep before releasing via malloc_trim in free().
• Mmap_threshold: The request size threshold for using mmap() to service a request. Requests of at least this size that cannot be allocated using already-existing space will be serviced via mmap.
• Arena max: The maximum number of arenas. If not set manually, the default formula is nr_cpu * (sizeof(long) == 4 ? 2 : 8).