@Scheduled 与 ThreadPoolTaskScheduler 行为

Question

我有这个作为配置

 @Bean
    public ThreadPoolTaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
        taskScheduler.setPoolSize(3);
        taskScheduler.setThreadNamePrefix("worker-thread-");
        return taskScheduler;
    }

Poller.java 每 100 毫秒轮询一次

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class Poller {

    private Processor processor

    @Autowired
    public SqsPoller(Processor processor) {
        this.processor = processor;
    }

    @Scheduled(fixedRate = 100)
    public void poll() throws InterruptedException {
        log.info("polling");
        processor.processMessages();
    }
}

Processor.java 做某事需要 5 秒左右的例子

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

@Slf4j
@Component
public class Processor {
    public void processMessages() throws InterruptedException {
        log.info("processing message and sleep 5 seconds");
        Thread.sleep(5000);
    }
}

当我运行它时，这是输出

      2018-11-02 21:13:43.029  INFO 6642 --- [   worker-thread-1]: polling 
        2018-11-02 21:13:43.029  INFO 6642 --- [   worker-thread-1]: processing message and sleep 5 seconds
        2018-11-02 21:13:48.034  INFO 6642 --- [   worker-thread-2]: polling 
        2018-11-02 21:13:48.035  INFO 6642 --- [   worker-thread-2]: processing message and sleep 5 seconds
        2018-11-02 21:13:53.037  INFO 6642 --- [   worker-thread-2]: polling 
        2018-11-02 21:13:53.037  INFO 6642 --- [   worker-thread-2]: processing message and sleep 5 seconds
....
        2018-11-02 21:14:53.078  INFO 6642 --- [   worker-thread-1]: polling 
        2018-11-02 21:14:53.078  INFO 6642 --- [   worker-thread-1]: processing message and sleep 5 seconds
        2018-11-02 21:14:58.081  INFO 6642 --- [   worker-thread-1]: polling 
        2018-11-02 21:14:58.082  INFO 6642 --- [   worker-thread-1]: processing message and sleep 5 seconds
        2018-11-02 21:15:03.086  INFO 6642 --- [   worker-thread-1]: polling 
        2018-11-02 21:15:03.087  INFO 6642 --- [   worker-thread-1]: processing message and sleep 5 seconds
    ....
        2018-11-02 21:16:38.148  INFO 6642 --- [   worker-thread-1]: polling 
        2018-11-02 21:16:38.148  INFO 6642 --- [   worker-thread-1]: processing message and sleep 5 seconds
        2018-11-02 21:16:43.153  INFO 6642 --- [   worker-thread-2]: polling 
        2018-11-02 21:16:43.153  INFO 6642 --- [   worker-thread-2]: processing message and sleep 5 seconds
....
        2018-11-02 21:21:48.339  INFO 6642 --- [   worker-thread-3]: polling 
        2018-11-02 21:21:48.339  INFO 6642 --- [   worker-thread-3]: processing message and sleep 5 seconds
        2018-11-02 21:21:53.345  INFO 6642 --- [   worker-thread-3]: polling 
        2018-11-02 21:21:53.345  INFO 6642 --- [   worker-thread-3]: processing message and sleep 5 seconds

如您所见，没有发生多线程，似乎线程 1 轮询和处理，并且它自己再次开始轮询和处理或另一个线程，但在任何给定时间只有一个线程在执行。

我还以为至少有3个线程在并行执行，因为触发3个线程只需要300毫秒。每个都需要 5 秒才能完成，因此在至少一个线程完成之前不会安排其他任何事情。

我是否 misunderstand/misconfigure 以某种方式让 3 个线程运行并行？

谢谢

Answer 1

所以为了让它并行执行任务，我需要做两件事 1.配置上的@EnableAsync 2、将上面的processMessage注解为@Async如下

@Async
public void processMessages() {
  ...
}

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