Spring Boot @Async 异步任务执行方法
1、任务执行和调度
Spring用TaskExecutor和TaskScheduler接口提供了异步执行和调度任务的抽象。
Spring的TaskExecutor和java.util.concurrent.Executor接口时一样的,这个接口只有一个方法execute(Runnable task)。
1.1、TaskExecutor类型
Spring已经内置了许多TaskExecutor的实现,你没有必要自己去实现:
- SimpleAsyncTaskExecutor 这种实现不会重用任何线程,每次调用都会创建一个新的线程。
- SyncTaskExecutor 这种实现不会异步的执行
- ConcurrentTaskExecutor 这种实现是java.util.concurrent.Executor的一个adapter。
- SimpleThreadPoolTaskExecutor 这种实现实际上是Quartz的SimpleThreadPool的一个子类,它监听Spring的声明周期回调。
- ThreadPoolTaskExecutor 这是最常用最通用的一种实现。它包含了java.util.concurrent.ThreadPoolExecutor的属性,并且用TaskExecutor进行包装。
1.2、注解支持调度和异步执行
To enable support for @Scheduled and @Async annotations add @EnableScheduling and @EnableAsync to one of your
@Configuration classes: @Configuration @EnableAsync @EnableScheduling public class AppConfig { }
特别注意
The default advice mode for processing @Async annotations is "proxy" which allows for interception of calls through the proxy only; local calls within the same class cannot get intercepted that way. For a more advanced mode of interception, consider switching to "aspectj" mode in combination with compile-time or load-time weaving.
默认是用代理去处理@Async的,因此,相同类中的方法调用带@Async的方法是无法异步的,这种情况仍然是同步。
举个例子:下面这种,在外部直接调用sayHi()是可以异步执行的,而调用sayHello()时sayHi()仍然是同步执行
public class A { public void sayHello() { sayHi(); } @Async public void sayHi() { } }
1.3、@Async注解
在方法上加@Async注解表示这是一个异步调用。换句话说,方法的调用者会立即得到返回,并且实际的方法执行是想Spring的TaskExecutor提交了一个任务。
In other words, the caller will return immediately upon invocation and the actual execution of the method will occur in a task that has been submitted to a Spring TaskExecutor.
@Async void doSomething() { // this will be executed asynchronously }
@Async void doSomething(String s) { // this will be executed asynchronously }
@Async Future<String> returnSomething(int i) { // this will be executed asynchronously }
注意:
@Async methods may not only declare a regular java.util.concurrent.Future return type but also Spring's org.springframework.util.concurrent.ListenableFuture or, as of Spring 4.2, JDK 8's java.util.concurrent.CompletableFuture: for richer interaction with the asynchronous task and for immediate composition with further processing steps.
1.4、@Async限定Executor
默认情况下,当在方法上加@Async注解时,将会使用一个支持注解驱动的Executor。然而,@Async注解的value值可以指定一个别的Executor
@Async("otherExecutor") void doSomething(String s) { // this will be executed asynchronously by "otherExecutor" }
这里,otherExecutor是Spring容器中任意Executor bean的名字。
1.5、@Async异常管理
当一个@Async方法有一个Future类型的返回值时,就很容易管理在调Future的get()方法获取任务的执行结果时抛出的异常。如果返回类型是void,那么异常是不会被捕获到的。
public class MyAsyncUncaughtExceptionHandler implements AsyncUncaughtExceptionHandler { @Override public void handleUncaughtException(Throwable ex, Method method, Object... params) { // handle exception } }
2、线程池配置
import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.scheduling.annotation.EnableAsync; import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor; @Configuration @EnableAsync public class TaskExecutorConfig { private Integer corePoolSize = 30; private Integer maxPoolSize = 50; private Integer keepAliveSeconds = 300; // private Integer queueCapacity = 2000; @Bean("myThreadPoolTaskExecutor") public ThreadPoolTaskExecutor myThreadPoolTaskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(corePoolSize); executor.setMaxPoolSize(maxPoolSize); executor.setKeepAliveSeconds(keepAliveSeconds); // executor.setQueueCapacity(queueCapacity); executor.setWaitForTasksToCompleteOnShutdown(true); executor.initialize(); return executor; } }
调用
@Async("myThreadPoolTaskExecutor") @Override public void present(CouponPresentLogEntity entity) { try { CouponBaseResponse rst = couponSendRpcService.send(entity.getUserId(), entity.getCouponBatchKey(), "1", entity.getVendorId()); if (null != rst && rst.isSuccess()) { entity.setStatus(PresentStatusEnum.SUCCESS.getType()); }else { String reason = (null == rst) ? "响应异常" : rst.getMsg(); entity.setFailureReason(reason); entity.setStatus(PresentStatusEnum.FAILURE.getType()); } }catch (Exception ex) { log.error(ex.getMessage(), ex); entity.setFailureReason(ex.getMessage()); entity.setStatus(PresentStatusEnum.FAILURE.getType()); } couponPresentLogDao.update(entity); }
结果
[INFO ] 2018-05-09 16:27:39.887 [myThreadPoolTaskExecutor-1] [com.ourhours.coupon.rpc.dubbo.ReceiveLogFilter] - receive method-name:send; arguments:[10046031,"4d7cc32f8f7e4b00bca56f6bf4b3b658","1",10001]
[INFO ] 2018-05-09 16:27:39.889 [myThreadPoolTaskExecutor-2] [com.ourhours.coupon.rpc.dubbo.ReceiveLogFilter] - receive method-name:send; arguments:[10046031,"4d7cc32f8f7e4b00bca56f6bf4b3b658","1",10001]
参考:
Spring Framework Reference Documentation 4.3.17.RELEASE
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