Asynchronous programming

Asynchronous programming is a way of dealing with slow and unpredictable resources. Rather than waiting idly for resources to become available, asynchronous programs can handle multiple resources concurrently and efficiently. Programming in an asynchronous way can be challenging because it is necessary to deal with external requests that can arrive in any order, may take a variable amount of time, or may fail unpredictably. In this section, we will introduce the topic by explaining the main concepts and terminology as well as by giving an idea of how asynchronous programs work.

Waiting for input/output

A modern computer employs different kinds of memory to store data and perform operations. In general, a computer possesses a combination of expensive memory that is capable of operating efficiently and cheaply and more abundant memory that is slower and is used to store a larger amount of data.

The memory hierarchy is shown in the following diagram:

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