Spring boot @Async @EnableAsync 註解 實現多線程

多線程執行過程

1. 若是此時線程池中的數量小於corePoolSize，即便線程池中的線程都處於空閒狀態，也要建立新的線程來處理被添加的任務。
2. 若是此時線程池中的數量等於corePoolSize，可是緩衝隊列 workQueue未滿，那麼任務被放入緩衝隊列。
3. 若是此時線程池中的數量大於corePoolSize，緩衝隊列workQueue滿，而且線程池中的數量小於maxPoolSize，建新的線程來處理被添加的任務。
4. 若是此時線程池中的數量大於corePoolSize，緩衝隊列workQueue滿，而且線程池中的數量等於maxPoolSize，那麼經過handler所指定的策略來處理此任務。也就是：處理任務的優先級爲：核心線程corePoolSize、任務隊列workQueue、最大線程 maximumPoolSize，若是三者都滿了，使用handler處理被拒絕的任務。
5. 當線程池中的線程數量大於corePoolSize時，若是某線程空閒時間超過keepAliveTime，線程將被終止。這樣，線程池能夠動態的調整池中的線程數。

配置類

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

    [@Bean](https://my.oschina.net/bean)
    public Executor getExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        // 線程池維護線程的最少數量
        executor.setCorePoolSize(5);
        // 線程池維護線程的最大數量
        executor.setMaxPoolSize(10);
        // 緩存隊列
        executor.setQueueCapacity(25);
        // 線程池初始化
        executor.initialize();
        return executor;
    }
}

異步任務

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

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

測試類

/**
 * @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);
        }

    }
}

執行結果

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