Spring线程池ThreadPoolTaskExecutor配置及详情
1. 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
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
@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
* @author daniel.zhao
*
*/
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 {
}