[SpringBoot]RestTemplateでReadTimeoutを意図的に発生させる

SpringBoot+Kotlinで外部APIの読み込みが遅延した場合を想定して、ReadTimeoutを起こしてみる。

呼び出し側
RestTemplateのReadTimeoutを3秒に設定

    private var restTemplate: RestTemplate? = null
    
    init {
        restTemplate = restTemplateBuilder
                .setConnectTimeout(Duration.ofSeconds(3))
                .setReadTimeout(Duration.ofSeconds(3))
                .build()
    }

    fun getTask(taskId: Int): Task? {
        val uri = "$taskApiUrl/tasks/$taskId"

        return restTemplate?.getForObject(uri, Task::class)
    }

外部API側
リクエストを５秒間Sleepする外部APIを用意しておく。

    @GetMapping("/{taskId}")
    @ResponseBody
    @ResponseStatus(HttpStatus.OK)
    fun getTask(@PathVariable("taskId") taskId: Int): Task {

        println("requst start for $taskId")
        sleep(5000)
        println("request end  for $taskId")

        return Task(
                taskId = taskId,
                title = "タスクのタイトル",
                description = "タスクの詳細説明",
                created = Date())
    }

実行
http://localhost:8080/tasks/12345

2020-12-09 08:23:36.447  INFO 4147 --- [nio-8080-exec-6] c.e.b.controller.TasksController         : getTask is called with taskId(12345).

2020-12-09 08:23:39.454 ERROR 4147 --- [nio-8080-exec-6] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:50000/tasks/12345": Read timed out; nested exception is java.net.SocketTimeoutException: Read timed out] with root cause

java.net.SocketTimeoutException: Read timed out
	at java.base/sun.nio.ch.NioSocketImpl.timedRead(NioSocketImpl.java:283) ~[na:na]
	at java.base/sun.nio.ch.NioSocketImpl.implRead(NioSocketImpl.java:309) ~

・・・省略・・・

3秒経ってReadTimeoutが発生するのを確認。