Detecting Leaks: dheap –leaks

The dheap –leaks command locates memory blocks that your program allocated and are no longer refe enced. It then displays a report that describes these blocks; for example:

d1.<> dheap -leaks

process 1 (32188): total count 9, total bytes 450
* leak 1 -- total count 9 (100.00%), total bytes 450 (100%)

-- smallest / largest / average leak: 10 / 90 / 50
: malloc PC=0x40021739 [/.../malloc_wrappers_dlopn.c]

: main PC=0x0804851e [/.../local_leak.cxx]
: __libc_start_main PC=0x40055647 [/lib/i686/libc.so.6]

: _start PC=0x080483f1 [/.../local_leak]

If you use the –check_interior option, MemoryScape considers a block as being referenced if a pointer exists to memory inside the block.

In addition to providing backtrace information, the CLI:

Consolidates leaks made by one program statement into one leak report. For example, leak 1 has nine instances.

Reports the amount of memory consumed for a group of leaks. It also tells you what percentage of leaked memory this one group of memory is using.

Indicates the smallest and largest leak size, as well as telling you what the average leak size is for a group.

You might want to paint a memory block when it is deallocated so that you can recognize that the data pointed to is out-of-date. Tagging the block so that you can be notified when it is deallocated is another way to locate the source of problems.