Just from glancing at your code, and knowing what memory gluttens packages are, I can see one giant problem. You have a loop which makes 10000 iterations, and in each cycle, you create a new $chart object and it's associated helper objects.

For some reason, I believe your sub mysub{} closure isn't cleaning up all those objects, as you would expect.

In my experience with other graphic modules, this can be avoided by creating only 1 set of global objects, and as you go thru your loops, you clean out and reuse the global object. This prevents the memory problem ... reuse your objects. See perldoc -q clear for how to clear a package. MJD's example code cleans out a package for reuse.