Non-blocking Spring Boot with Kotlin Coroutines

Posted 2021-04-26 Kotlin 开发者社区

Non-blocking Spring Boot with Kotlin Coroutines

1. Overview

Kotlin Coroutines can often add readability to reactive, callback-heavy code.

In this tutorial, we’ll find out how to leverage these coroutines for building non-blocking Spring Bootapplications. We’ll also compare the reactive and coroutine approaches.

2. Coroutine Motivation

Nowadays, it is common for systems to serve thousands or even millions of requests. Consequently, the development world is moving towards non-blocking computation and request handling. Utilizing system resource efficiently, by offloading I/O operations from core threads makes it possible to handle many more requests compared to the traditional thread per-request approach.

Asynchronous processing is not a trivial task and can be error-prone. Fortunately, we have tools for tackling this complexity like Java CompletableFutures or reactive libraries like RxJava. Indeed, the Spring framework already supports reactive approaches with the Reactor and WebFlux frameworks.

Asynchronous code can be hard to read, but the Kotlin language provides the concept of Coroutines to allow writing concurrent and asynchronous code in a sequential style.

Coroutines are very flexible, so we have more control over the execution of tasks via Jobs and Scopes. Besides that, Kotlin coroutines work perfectly side by side with existing Java non-blocking frameworks.

Spring will support Kotlin Coroutines from version 5.2.

3. Project Setup

Let’s start by adding in the dependencies we’ll need.

As most of the dependencies used in this tutorial don’t have stable releases yet, we’ll need to include the snapshots and milestones repositories:

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