AWS Step Function cost calculation for parallel tasks

Question

I am trying to calculate the cost of my AWS Step Function statemachine. I get that each state transition costs a price x but I am not quite sure how transitions are calculated when it comes to parallel tasks.

Let's say I have 3 individual tasks in a parallel task. Clearly that would count as at least 3 state transitions but does the transition to the parallel task come on top of that? Also: does the transition out of the parallel task only count as one transition?

I could unfortunately not find documentation that clearly answers my question.

Thanks a lot

Answer 1

Looking at the Pricing Example #2: Application Workflow with Multiple Paths, it looks like the cost for Parallel tasks are:

• Transition from previous state into the parallel state
• Transition from parallel state into each branch
• Transition out of the parallel

So for your 3 parallel states, you would be charged for 5 transitions

• 1 from previous state into parallel state
• 3 from parallel into branches
• 1 out of parallel state

IMHO this is not very clear as to what's being charged where. But if you think of it as each state transition is a cost. Into a parallel is one change, then within the parallel each branch is another and finally out of the parallel into another state.