there is a better way - in any unbounded compute loop, add some code to check for cancellation. it can be very very very cheap

this is not possible if you are calling third party code that you can't modify. in this case it's probably a better idea to run it on another process and use shared memory to communicate back results. this can even be done in an airtight sandboxed manner (browsers do this for example), something that can't really be done with threads