线程池ThreadPoolExecutor执行任务Runnable乱序特性
接口Runnable在线程池ThreadPoolExecutor的队列中是按顺序取出,执行却是乱序的。
线程执行代码如下:
- @Slf4j
- public class TheRunnable implements Runnable {
-
- private String username;
-
- public String getUsername() {
- return username;
- }
-
- public void setUsername(String username) {
- this.username = username;
- }
-
- public TheRunnable(String username){
- super();
- this.username=username;
- }
-
-
-
- @Override
- public void run() {
- try {
- Thread.sleep(2000);
- log.info("线程名:"+username);
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
运行类代码如下:
- public class DisorderedOrderRun {
- public static void main(String[] args) {
- ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 10, TimeUnit.SECONDS, new LinkedBlockingQueue<>());
- for (int i = 0; i < 20; i++) {
- TheRunnable theRunnable = new TheRunnable("G" + (i + 1));
- threadPoolExecutor.execute(theRunnable);
- }
- }
- }
运行结果如下:
- 10:37:06.675 [pool-1-thread-5] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G5
- 10:37:06.660 [pool-1-thread-3] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G3
- 10:37:06.675 [pool-1-thread-1] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G1
- 10:37:06.660 [pool-1-thread-2] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G2
- 10:37:06.706 [pool-1-thread-4] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G4
- 10:37:08.692 [pool-1-thread-3] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G6
- 10:37:08.692 [pool-1-thread-1] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G7
- 10:37:08.692 [pool-1-thread-5] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G8
- 10:37:08.692 [pool-1-thread-2] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G9
- 10:37:08.723 [pool-1-thread-4] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G10
- 10:37:10.708 [pool-1-thread-3] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G11
- 10:37:10.708 [pool-1-thread-1] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G12
- 10:37:10.708 [pool-1-thread-5] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G13
- 10:37:10.708 [pool-1-thread-2] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G14
- 10:37:10.739 [pool-1-thread-4] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G15
- 10:37:12.714 [pool-1-thread-1] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G17
- 10:37:12.714 [pool-1-thread-3] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G16
- 10:37:12.714 [pool-1-thread-5] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G18
- 10:37:12.714 [pool-1-thread-2] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G19
- 10:37:12.745 [pool-1-thread-4] INFO com.ozx.concurrentprogram.executor.service.TheRunnable - 线程名:G20
从运行结果看出Runnable状态从就绪态到运行态转换,线程各自获取CPU时间片不一样,所以线程执行顺序是乱序的。
通过使用线程池能最大幅度地减少创建线程对象的内存与CPU开销,加快程序运行效率,进而对创建线程类的代码进行了封装。