Spring线程池ThreadPoolTaskExecutor配置及详情

墨蓝 2022-05-14 00:08 443阅读 0赞

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## 1. ThreadPoolTaskExecutor配置 ##

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1            
     2     <bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
     3         
     4         <property name="corePoolSize" value="5" />
     5         
     6         <property name="keepAliveSeconds" value="200" />
     7         
     8         <property name="maxPoolSize" value="10" />
     9         
    10         <property name="queueCapacity" value="20" />
    11         
    12         <property name="rejectedExecutionHandler">
    13             <bean class="java.util.concurrent.ThreadPoolExecutor$CallerRunsPolicy" />
    14         </property>
    15     </bean>

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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

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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     @Test
    12     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 }

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MultiThreadDemo

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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     @Override
    18     public void run() {
    19         multiThreadProcessService.processSomething();
    20     }
    21 
    22 }

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MultiThreadProcessService

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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 }

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MultiThreadConfig

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

[copycode.gif]: /images/20220514/79b30026a2154a7f93ee172e570f3536.png