Spring boot @Async @EnableAsync 注解 实现多线程

多线程执行过程

1. 若是此时线程池中的数量小于corePoolSize，即便线程池中的线程都处于空闲状态，也要建立新的线程来处理被添加的任务。
2. 若是此时线程池中的数量等于corePoolSize，可是缓冲队列 workQueue未满，那么任务被放入缓冲队列。
3. 若是此时线程池中的数量大于corePoolSize，缓冲队列workQueue满，而且线程池中的数量小于maxPoolSize，建新的线程来处理被添加的任务。
4. 若是此时线程池中的数量大于corePoolSize，缓冲队列workQueue满，而且线程池中的数量等于maxPoolSize，那么经过handler所指定的策略来处理此任务。也就是：处理任务的优先级为：核心线程corePoolSize、任务队列workQueue、最大线程 maximumPoolSize，若是三者都满了，使用handler处理被拒绝的任务。
5. 当线程池中的线程数量大于corePoolSize时，若是某线程空闲时间超过keepAliveTime，线程将被终止。这样，线程池能够动态的调整池中的线程数。

配置类

/**
 * [@author](https://my.oschina.net/arthor) Mr.Krab
 * [@date](https://my.oschina.net/u/2504391) 2019-03-05 09:39
 */
@Configuration
@EnableAsync // 启用多线程
public class AsyncConfig {

    [@Bean](https://my.oschina.net/bean)
    public Executor getExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        // 线程池维护线程的最少数量
        executor.setCorePoolSize(5);
        // 线程池维护线程的最大数量
        executor.setMaxPoolSize(10);
        // 缓存队列
        executor.setQueueCapacity(25);
        // 线程池初始化
        executor.initialize();
        return executor;
    }
}

异步任务

/**
 * @author Mr.Krab
 * @date 2019-03-05 09:45
 */
@Service
@Slf4j
public class AsyncService {

    @Async //异步任务
    public void executeAsync(int i) {
        log.info("current thread {}, i = {}", Thread.currentThread().getName(), i);
    }
}

测试类

/**
 * @author Mr.Krab
 * @date 2019-03-05 09:48
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class AsyncTest {

    @Autowired
    private AsyncService asyncService;
	
    @Test
    public void testAsync(){
        for(int i =0; i< 10;i++){
            asyncService.executeAsync(i);
        }

    }
}

执行结果

2019-03-05 09:55:10.470  INFO 18644 --- [  getExecutor-4] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-4, i = 3
2019-03-05 09:55:10.470  INFO 18644 --- [  getExecutor-5] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-5, i = 4
2019-03-05 09:55:10.470  INFO 18644 --- [  getExecutor-1] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-1, i = 0
2019-03-05 09:55:10.470  INFO 18644 --- [  getExecutor-3] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-3, i = 2
2019-03-05 09:55:12.163  INFO 18644 --- [  getExecutor-1] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-1, i = 7
2019-03-05 09:55:10.470  INFO 18644 --- [  getExecutor-2] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-2, i = 1
2019-03-05 09:55:11.019  INFO 18644 --- [  getExecutor-4] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-4, i = 5
2019-03-05 09:55:11.715  INFO 18644 --- [  getExecutor-5] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-5, i = 6
2019-03-05 09:55:12.587  INFO 18644 --- [  getExecutor-3] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-3, i = 8
2019-03-05 09:55:13.651  INFO 18644 --- [  getExecutor-1] cn.misterkrab.demo.async.AsyncService    : current thread getExecutor-1, i = 9