You could build or obtain a perl built with DEBUGGING on, to make the -D options work. The memory accounting of -Dm also requires that you build for perl's memory allocator rather than system malloc.

See perlrun for a list of the -D flags.

It's hard to say without seeing code, but one usual suspect for memory running away in long-running perl programs is a global hash (lexical or not). If data is added to one each cycle and never deleted . . .