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Spring线程池ThreadPoolTaskExecutor配置及详情

ThreadPoolTaskExecutor配置

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

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。

示例代码

Junit Test

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = { MultiThreadConfig.class })
public class MultiThreadTest {

    @Autowired
    private ThreadPoolTaskExecutor taskExecutor;

    @Autowired
    private MultiThreadProcessService multiThreadProcessService;

    @Test
    public void test() {

        int n = 20;
        for (int i = 0; i < n; i++) {
            taskExecutor.execute(new MultiThreadDemo(multiThreadProcessService));
            System.out.println("int i is " + i + ", now threadpool active threads totalnum is " + taskExecutor.getActiveCount());
        }

        try {
            System.in.read();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

MultiThreadDemo

/**
 * 多线程并发处理demo
 */
public class MultiThreadDemo implements Runnable {

    private MultiThreadProcessService multiThreadProcessService;

    public MultiThreadDemo() {
    }

    public MultiThreadDemo(MultiThreadProcessService multiThreadProcessService) {
        this.multiThreadProcessService = multiThreadProcessService;
    }

    @Override
    public void run() {
        multiThreadProcessService.processSomething();
    }

}

MultiThreadProcessService

@Service
public class MultiThreadProcessService {

    public static final Logger logger = Logger.getLogger(MultiThreadProcessService.class);

    /**
     * 默认处理流程耗时1000ms
     */
    public void processSomething() {
        logger.debug("MultiThreadProcessService-processSomething" + Thread.currentThread() + "......start");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        logger.debug("MultiThreadProcessService-processSomething" + Thread.currentThread() + "......end");
    }
}

MultiThreadConfig

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