Task Execution and Scheduling In SpringBoot

开天辟地

• Task Execution and Scheduling

In the absence of an Executor bean in the context, Spring Boot auto-configures a ThreadPoolTaskExecutor with sensible defaults that can be automatically associated to asynchronous task execution (@EnableAsync) and Spring MVC asynchronous request processing.

在上下文中没有Executor bean的情况下，Spring Boot会自动配置一个ThreadPoolTaskExecutor，其中包含合理的默认值，可以自动关联到异步任务执行（@EnableAsync）和Spring MVC异步请求处理。

• How To Do @Async in Spring

By default, Spring uses a SimpleAsyncTaskExecutor to actually run these methods asynchronously. But we can override the defaults at two levels: the application level or the individual method level.

Spring使用SimpleAsyncTaskExecutor来实际以异步方式运行这些方法。但是我们可以在两个级别上覆盖默认设置：应用程序级别或单个方法级别。

在@EnableAsync的javadoc中也有相关的一段话作为关联佐证:

By default, Spring will be searching for an associated thread pool definition: either a unique org.springframework.core.task.TaskExecutor bean in the context, or an java.util.concurrent.Executor bean named "taskExecutor" otherwise. If neither of the two is resolvable, a org.springframework.core.task.SimpleAsyncTaskExecutor will be used to process async method invocations. Besides, annotated methods having a void return type cannot transmit any exception back to the caller. By default, such uncaught exceptions are only logged.

要么是上下文中唯一的 org.springframework.core.task.TaskExecutor bean，要么是名为 "taskExecutor" 的 java.util.concurrent.Executor bean。如果这两者都无法解析，则会使用 org.springframework.core.task.SimpleAsyncTaskExecutor 来处理异步方法调用。此外，具有 void 返回类型的注释方法无法将任何异常传递回调用者。默认情况下，这样的未捕获异常仅会被记录日志。

解答

Spring Boot会自动配置一个ThreadPoolTaskExecutor, 它属于TaskExecutor, 如果是唯一的话就满足了相关条件, 不会再使用org.springframework.core.task.SimpleAsyncTaskExecutor运行@Async的方法

1. Task Execution

1.1. 注解

• @EnableAsync/@Async

1.2 重点类

ThreadPoolTaskExecutor

1.3 常规配置

spring.task.execution.pool.max-size=16
spring.task.execution.pool.queue-capacity=100
spring.task.execution.pool.keep-alive=10s

1.4 额外配置

默认的拒绝策略是AbortPolicy, 如果要修改的话就没有办法通过application.yaml设置了, 需要参考- How To Do @Async in Spring

2. Task Scheduling

1.1 注解

• @EnableScheduling/@Scheduled

1.2 重点类

ThreadPoolTaskScheduler

1.3 常规配置

spring.task.scheduling.thread-name-prefix=scheduling-
spring.task.scheduling.pool.size=2

1.4 额外配置

一般不涉及额外配置