malloc_history

NAME
     malloc_history -- Show the malloc allocations that the process has performed
     
SYNOPSIS
     malloc_history pid address
     malloc_history pid -all_by_size
     malloc_history pid -all_by_count

DESCRIPTION
     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 deallocations
     that have manipulated a buffer at that address.  For each allocation,
     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 allocations
     by address, also set the environment variable MallocStackLoggingNoCompact
     to 1.

     malloc_history is particularly useful for tracking down memory smashers.
     Run the program to be inspected with MallocStackLogging and MallocStackLoggingNoCompact
     defined.  Also set the environment variable MallocScribble;
     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 malloc
     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_history
     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.

SEE ALSO
     malloc(3), heap(1), leaks(1), vmmap(1)

     Similar graphical applications are part of the developer tools for the
     system.  MallocDebug.app is a graphical application that also provides
     information about heap-allocated memory.  It also performs leak analysis.
     Sampler.app is a graphical application for sampling program behavior.

BSD                             April 26, 2000                             BSD