Chapter 8. Futures
The first step towards reactive applications is to break out of synchronous processing. In general, applications waste a lot of time waiting for things to happen. Maybe we are waiting on an expensive computation—say, calculating the 1000th Fibonacci number. Perhaps we are waiting for some information to be written to the database. We could also be waiting for a network call to return, bringing us the latest recommendations from our favorite online store.
Regardless of what we're waiting for, we should never block clients of our application. This is crucial to achieve the responsiveness we desire when building reactive systems.
In an age where processing cores are abundant—my MacBook Pro has eight processor cores—blocking APIs severely underutilizes the resources we have at our disposal.
As we approach the end of this book, it is appropriate to step back a little and appreciate that not all classes of problems that deal with concurrent, asynchronous computations require the...
