malloc_history(1) BSD General Commands Manual malloc_history(1)
malloc_history -- Show the malloc allocations that the process has per- formed
malloc_history pid address malloc_history pid -all_by_size malloc_history pid -all_by_count
malloc_history inspects a given process and lists the malloc allocations performed by it. malloc_history relies on information provided by the standard malloc library when debugging options have been turned on. By specifying an address, malloc_history lists the allocations and deal- locations that have manipulated a buffer at that address. For each allo- cation, a stack trace describing who called malloc or free is listed. Alternatively, the -all_by_size and -all_by_count options will list all allocations. Frequent allocations from the same point in the program (that is, the same call stack) are grouped together, and output presented either from largest allocations to smallest, or most allocations to least. All modes require the standard malloc library's debugging facility to be turned on. To do this, set the environment variable MallocStackLogging to 1 in the shell that will run the program. To be able to examine allo- cations by address, also set the environment variable MallocStackLogging- NoCompact to 1. malloc_history is particularly useful for tracking down memory smashers. Run the program to be inspected with MallocStackLogging and MallocStack- LoggingNoCompact defined. Also set the environment variable MallocScrib- ble; this causes the malloc library to overwrite freed memory with a well-known value (0x55), and occasionally checks freed buffers to make sure the memory has not been overwritten since it was cleared. When mal- loc detects the memory has been written, it will print out a warning that the buffer was modified after being freed. You can then use malloc_his- tory to find who allocated and freed memory at that address, and thus deduce what parts of the code might still have a pointer to the freed structure.
malloc(3), heap(1), leaks(1), vmmap(1) The developer tools for the system also include a graphical application, /Developer/Applications/Instruments.app, that provides instruments that give information similar to that provided by malloc_history. The Objec- tAlloc instrument graphically displays dynamic, real-time information about the object and memory use in an application, including backtraces of where the allocations occured. BSD March 15, 2007 BSD
Mac OS X 10.7 - Generated Sat Nov 5 05:45:47 CDT 2011