Spring线程池ThreadPoolTaskExecutor配置及详情

1. ThreadPoolTaskExecutor配置

 1 <!-- spring thread pool executor -->            2     <bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor"> 3         <!-- 线程池维护线程的最少数量 --> 4         <property name="corePoolSize" value="5" /> 5         <!-- 允许的空闲时间 --> 6         <property name="keepAliveSeconds" value="200" /> 7         <!-- 线程池维护线程的最大数量 --> 8         <property name="maxPoolSize" value="10" /> 9         <!-- 缓存队列 -->10         <property name="queueCapacity" value="20" />11         <!-- 对拒绝task的处理策略 -->12         <property name="rejectedExecutionHandler">13             <bean class="java.util.concurrent.ThreadPoolExecutor$CallerRunsPolicy" />14         </property>15     </bean>

属性字段说明

corePoolSize：线程池维护线程的最少数量

keepAliveSeconds：允许的空闲时间

maxPoolSize：线程池维护线程的最大数量

queueCapacity：缓存队列

rejectedExecutionHandler：对拒绝task的处理策略

2. execute(Runable)方法执行过程

如果此时线程池中的数量小于corePoolSize，即使线程池中的线程都处于空闲状态，也要创建新的线程来处理被添加的任务。

如果此时线程池中的数量等于 corePoolSize，但是缓冲队列 workQueue未满，那么任务被放入缓冲队列。

如果此时线程池中的数量大于corePoolSize，缓冲队列workQueue满，并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。

如果此时线程池中的数量大于corePoolSize，缓冲队列workQueue满，并且线程池中的数量等于maxPoolSize，那么通过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，如果三者都满了，使用handler处理被拒绝的任务。

当线程池中的线程数量大于corePoolSize时，如果某线程空闲时间超过keepAliveTime，线程将被终止。这样，线程池可以动态的调整池中的线程数。

3. 示例代码

Junit Test

 1 @RunWith(SpringJUnit4ClassRunner.class) 2 @ContextConfiguration(classes = { MultiThreadConfig.class }) 3 public class MultiThreadTest { 4  5     @Autowired 6     private ThreadPoolTaskExecutor taskExecutor; 7  8     @Autowired 9     private MultiThreadProcessService multiThreadProcessService;10     11     @Test12     public void test() {13         14         int n = 20;15         for (int i = 0; i < n; i++) {16             taskExecutor.execute(new MultiThreadDemo(multiThreadProcessService));17             System.out.println("int i is " + i + ", now threadpool active threads totalnum is " + taskExecutor.getActiveCount());18         }19         20         try {21             System.in.read();22         } catch (IOException e) {23             throw new RuntimeException(e);24         }25     }26 }

MultiThreadDemo

 1 /** 2  * 多线程并发处理demo 3  * @author daniel.zhao 4  * 5  */ 6 public class MultiThreadDemo implements Runnable { 7  8     private MultiThreadProcessService multiThreadProcessService; 9     10     public MultiThreadDemo() {11     }12     13     public MultiThreadDemo(MultiThreadProcessService multiThreadProcessService) {14         this.multiThreadProcessService = multiThreadProcessService;15     }16     17     @Override18     public void run() {19         multiThreadProcessService.processSomething();20     }21 22 }

MultiThreadProcessService

 1 @Service 2 public class MultiThreadProcessService { 3  4     public static final Logger logger = Logger.getLogger(MultiThreadProcessService.class); 5      6     /** 7      * 默认处理流程耗时1000ms 8      */ 9     public void processSomething() {10         logger.debug("MultiThreadProcessService-processSomething" + Thread.currentThread() + "......start");11         try {12             Thread.sleep(1000);13         } catch (InterruptedException e) {14             throw new RuntimeException(e);15         }16         logger.debug("MultiThreadProcessService-processSomething" + Thread.currentThread() + "......end");17     }18 }

MultiThreadConfig

1 @Configuration2 @ComponentScan(basePackages = { "com.xxx.multithread" })3 @ImportResource(value = { "classpath:config/application-task.xml" })4 @EnableScheduling5 public class MultiThreadConfig {6 }