@briancavalier In line 12 to 17 I am creating all pending promises up front and ensuring that I have a way of being notified when the promise actually completes. The function called block is just their to create a scope so that the i value doesn't change in-between the call to then and the pending promise actually being resolved. The function passed to then will call whatever happens to be attached to the pending promises `__done__` property. Which I ensure is the done function that is passed into each iteration of the benchmark. This function just notifies the runner that the current iteration has been completed. Does that make sense?