Python Process Terminated due to "Low Swap" When Writing To stdout for Data Science

I'm new to python so I apologize for any misconceptions.

I have a python file that needs to read/write to stdin/stdout many many times (hundreds of thousands) for a large data science project. I know this is not ideal, but I don't have a choice in this case.

After about an hour of running (close to halfway completed), the process gets terminated on my mac due to "Low Swap" which I believe refers to lack of memory. Apart from the read/write, I'm hardly doing any computing and am really just trying to get this to run successfully before going any farther.

My Question: Does writing to stdin/stdout a few hundred thousand times use up that much memory? The file basically needs to loop through some large lists (15k ints) and do it a few thousand times. I've got 500 gigs of hard drive space and 12 gigs of ram and am still getting the errors. I even spun up an EC2 instance on AWS and STILL had memory errors. Is it possible that I have some sort of memory leak in the script even though I'm not doing hardly anything? Is there anyway that I reduce the memory usage to run this successfully?

Appreciate any help.