AWS Cloud costs can sometimes be hiding and never found unless you explicitly “seek” them out. For example,  AWS Glue costs are partially calculated on the time needed for them to run. 

So, ensure you take measures to protect yourself against this wasted cost:
> Be sure to monitor and create alerts for Glue jobs that run longer than your expected job execution time. This can help you identify hanging jobs that are doing nothing more than costing you money
> Ensure you write jobs efficiently as possible to eliminate wasted execution time. The better the code, the more money you save.
> Avoid sprawling code as much as possible. If you can avoid a Glue job that calls an external piece of code or process that is out of your control, do it. And if you can’t , then code smart to ensure your code exits when the external code does not go as planned. Avoiding this wasted time will save you money.