Devel::Leak has two functions: NoteSV and CheckSV.
 .
 NoteSV walks the perl internal table of allocated SVs (scalar values) - (which
 actually contains arrays and hashes too), and records their addresses in a
 table. It returns a count of these "things", and stores a pointer to the
 table (which is obtained from the heap using malloc()) in its argument.
 .
 CheckSV is passed argument which holds a pointer to a table created by
 NoteSV. It re-walks the perl-internals and calls sv_dump() for any "things"
 which did not exist when NoteSV was called. It returns a count of the number
 of "things" now allocated.