Asynchronous I/O is intended to avoid long waits only. These are blocking, indeterminate waits that usually depend on something from the network or an end user. Long waits also tend to be conditional, based on the current non-blocking mode. Short internal waits, such as lock waits for serialization, are not avoided. An example is that of a read: you can wait for a lock to look at the inbound queue, but if the queue is empty you cannot wait for the data.