Memory usage per top 10x usage per heapy

[MrsEntity]

Hi all,

I'm working on some code that parses a 500kb, 2M line file line by line and saves, per line, some derived strings into various data structures. I thus expect that memory use should monotonically increase. Currently, the program is taking up so much memory - even on 1/2 sized files - that on 2GB machine I'm thrashing swap. What's strange is that heapy (http://guppy-pe.sourceforge.net/) is showing that the code uses about 10x less memory than reported by top, and the heapy data seems consistent with what I was expecting based on the objects the code stores. I tried using memory_profiler (http://pypi.python.org/pypi/memory_profiler) but it didn't really provide any illuminating information. The code does create and discard a number of objects per line of the file, but they should not be stored anywhere, and heapy seems to confirm that. So, my questions are:

1) For those of you kind enough to help me figure out what's going on, what additional data would you like? I didn't want swamp everyone with the code and heapy/memory_profiler output but I can do so if it's valuable.
2) How can I diagnose (and hopefully fix) what's causing the massive memory usage when it appears, from heapy, that the code is performing reasonably?

Specs: Ubuntu 12.04 in Virtualbox on Win7/64, Python 2.7/64

Thanks very much.