I created a webcrawler that holds a lot of data in a list and then outputs this data to a file. When I try to run 50 instances of this program at the same time using a batch file, the programs suddenly all terminate at once, without outputting the text file. Is this due to a lack of memory?

It can be due to any exception whatsoever. To find out, you'll need to isolate the offending lines.

I often run my code through IDLE, which prints exceptions. There might be another solution that works.

Jeff