# Async: Avoiding Disaster and Unbounded Growth --- ## Information gathering Your project is dynamic: * Make it traceable * Constantly monitor --- ## Backpressure Backpressure is the process of "pushing back" on producers that are too fast. This throttles the system, but allows it to not fail. --- ## Bounded vs. unbounded growth * Bounded channels are predictable * Unbounded are more dynamic * Bounded provide backpressure * Unbounded are useful if you know they are never beyond a certain size --- ## Holding state * Tasks can hold state * Otherwise, Mutexes and RWlocks allow sharing --- ## Dropping futures * Dropping a future means cancelling it * Be aware of what happens if it is cancelled --- ## Shutting down * Make sure your signal handling is centralized * Every component should subscribe to a cancel notification --- ## Implementing a custom Future: Pinning * Futures are not allowed to move in Memory * The type that describes that is called `Pin` * Pinning is hard, but there's support libraries --- ## The poll protocol Futures are `poll` based - that means they get asked if they are complete. * This happens an infinite number of times, until they mark themselves complete * The process is optimised through the `Waker` type * Implementing poll yourself is rather easy
