func malloc(size):
  object = ... // alloc magic

  if random_sample():
    s = stacktrace()
    profile[s].allocs++
    profile[s].alloc_bytes += sizeof(object)
    track_profiled(object, s)

  return object

func sweep(object):
  // do gc stuff to free object

  if is_profiled(object)
    s = alloc_stacktrace(object)
    profile[s].frees++
    profile[s].free_bytes += sizeof(object)

  return object