4. 异步情况下使用线程池 InheritableThreadLocal的表现
在异步时InheritableThreadLocal没有发现异常，现在我们加上线程池，看看最终效果。
1）增加线程池
为了尽快看到效果，我们将线程的核心数和最大数都设置为2。
@Configuration
//@EnableAsync//开启注解：开启异步支持
public class ThreadPool {
private static final int CORE_POOL_SIZE = Runtime.getRuntime().availableProcessors() *2;
private static final int MAX_POOL_SIZE = CORE_POOL_SIZE *4 <256 ? 256 : CORE_POOL_SIZE * 4;
private static final int KEEP_ALIVE_TIME = 10; //允许线程空闲时间（单位为秒）
private static final int QUEUE_CAPACITY = 200; // 缓冲队列数
private static final int AWAIT_TERMINATION = 60;//线程池中任务的等待时间，如果超过这个时候还没有销毁就强制销毁
private static final Boolean WAIT_FOR_TASKS_TO_COMPLETE_ON_SHUTDOWN = true;//用来设置线程池关闭的时候等待所有任务都完成再继续销毁其他的Bean
private static final String THREAD_NAME_PREFIX = "PiceaAsync-Service-"; // 线程池名前缀
/**
* <p>"@Bean("piceaTaskExecutor")，Bean后面的（）内容可以省略
* 如果省略则使用方法名<p>
* @author jiangbing.yang
* @date 2019/3/27 11:07
* @params
* @return
* @throws
*/
@Bean("piceaTaskExecutor")
public static ThreadPoolTaskExecutorpiceaTaskExecutor () {
ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
taskExecutor.setCorePoolSize(2);
taskExecutor.setMaxPoolSize(2);
taskExecutor.setKeepAliveSeconds(KEEP_ALIVE_TIME);
taskExecutor.setQueueCapacity(QUEUE_CAPACITY);
taskExecutor.setThreadNamePrefix(THREAD_NAME_PREFIX);
taskExecutor.setWaitForTasksToCompleteOnShutdown(WAIT_FOR_TASKS_TO_COMPLETE_ON_SHUTDOWN);
taskExecutor.setAwaitTerminationSeconds(AWAIT_TERMINATION);
// 线程池对拒绝任务的处理策略
taskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
// 初始化
taskExecutor.initialize();
return taskExecutor;
}
}
2）在Service层增加方法
先增加接口
void testThreadLocalAsyncThreadPool() throws Exception;
然后增加实现
@Async("piceaTaskExecutor")
@Override
public void testThreadLocalAsyncThreadPool() throws Exception {
System.out.println("我是Service层处理线程，线程名：" + Thread.currentThread().getName());
System.out.println(" InheritableThreadLocalUtil保存的值为：" + InheritableThreadLocalUtil.getValue());
InheritableThreadLocalUtil.remove();
}
3）在Controller层增加测试方法
@RequestMapping("/testItlTl")
public String testInheritableThreadLocalThreadPool() throws Exception {
System.out.println("我是Controller层处理线程，线程名：" + Thread.currentThread().getName());
InheritableThreadLocalUtil.setValue("我是：testInheritableThreadLocal");
System.out.println("这里是处理过程，处理中.........");
System.out.println(" InheritableThreadLocalUtil保存的值为：" + InheritableThreadLocalUtil.getValue());
piceaService.testThreadLocalAsyncThreadPool();
return "testInheritableThreadLocalThreadPool:";
}
4）测试结果
浏览器中输入http://localhost:2001/testItlTl
运行3次，第1次和第2次中发现，可以取到父线程的值，第3次的时间，发现就取不到父线程设置的值。
Spring-boot-TL-ITLTL.png
5. 异步情况下使用线程池 TransmittableThreadLocal 的表现
在异步且使用线程池的情况下，InheritableThreadLocal已经出现问题，现在我们使用TransmittableThreadLocal 看看效果。
1）修改线程池，使用TTL的包装类
为了尽快看到效果，我们将线程的核心数和最大数都设置为2。主要是这一段“ TtlExecutors.getTtlExecutor(taskExecutor);”，这个是重点，这个是重点，这个是重点。重要的问题说三次。
@Configuration
//@EnableAsync//开启注解：开启异步支持
public class ThreadPool {
private static final int CORE_POOL_SIZE = Runtime.getRuntime().availableProcessors() *2;
private static final int MAX_POOL_SIZE = CORE_POOL_SIZE *4 <256 ? 256 : CORE_POOL_SIZE * 4;
private static final int KEEP_ALIVE_TIME = 10; //允许线程空闲时间（单位为秒）
private static final int QUEUE_CAPACITY = 200; // 缓冲队列数
private static final int AWAIT_TERMINATION = 60;//线程池中任务的等待时间，如果超过这个时候还没有销毁就强制销毁
private static final Boolean WAIT_FOR_TASKS_TO_COMPLETE_ON_SHUTDOWN = true;//用来设置线程池关闭的时候等待所有任务都完成再继续销毁其他的Bean
private static final String THREAD_NAME_PREFIX = "PiceaAsync-Service-"; // 线程池名前缀
/**
* <p>"@Bean("piceaTaskExecutor")，Bean后面的（）内容可以省略
* 如果省略则使用方法名<p>
* @author jiangbing.yang
* @date 2019/3/27 11:07
* @params
* @return
* @throws
*/
@Bean("piceaTaskExecutor")
public static Executor piceaTaskExecutor () {
ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
taskExecutor.setCorePoolSize(2);
taskExecutor.setMaxPoolSize(2);
taskExecutor.setKeepAliveSeconds(KEEP_ALIVE_TIME);
taskExecutor.setQueueCapacity(QUEUE_CAPACITY);
taskExecutor.setThreadNamePrefix(THREAD_NAME_PREFIX);
taskExecutor.setWaitForTasksToCompleteOnShutdown(WAIT_FOR_TASKS_TO_COMPLETE_ON_SHUTDOWN);
taskExecutor.setAwaitTerminationSeconds(AWAIT_TERMINATION);
// 线程池对拒绝任务的处理策略
taskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
// 初始化
taskExecutor.initialize();
// return taskExecutor;
return TtlExecutors.getTtlExecutor(taskExecutor);
}
}
2）在Service层增加方法
先增加接口
void testThreadLocalAsyncThreadPoolTtl() throws Exception;
然后增加实现
@Async("piceaTaskExecutor")
@Override
public void testThreadLocalAsyncThreadPoolTtl() throws Exception {
System.out.println("我是Service层处理线程，线程名：" + Thread.currentThread().getName());
System.out.println(" TransmittableThreadLocalUtil：" + TransmittableThreadLocalUtil.getValue());
TransmittableThreadLocalUtil.remove();
}
3）在Controller层增加测试方法
@RequestMapping("/testTtlTl")
public String testTransmittableThreadLocalThreadPool() throws Exception {
System.out.println("我是Controller层处理线程，线程名：" + Thread.currentThread().getName());
TransmittableThreadLocalUtil.setValue("我是：testTransmittableThreadLocalThreadPool");
System.out.println("这里是处理过程，处理中.........");
System.out.println(" TransmittableThreadLocalUtil保存的值为：" + TransmittableThreadLocalUtil.getValue());
piceaService.testThreadLocalAsyncThreadPoolTtl();
return "testInheritableThreadLocalThreadPool:";
}
4）测试结果
浏览器中输入http://localhost:2001/testTtlTl
运行3次以上，发现在都可以取到父线程的值。
Spring-boot-TL-TTLTL.png
6. 三个工具类的方法
1）ThreadLocalUtil
public class ThreadLocalUtil {
public static final ThreadLocal<String> THREAD_LOCAL = new ThreadLocal<>();
//设置线程需要保存的值
public static void setValue (String str) {
THREAD_LOCAL.set(str);
}
//获取线程中保存的值
public static String getValue() {
return THREAD_LOCAL.get();
}
//移除线程中保存的值
public static void remove() {
THREAD_LOCAL.remove();
}
}
2） InheritableThreadLocalUtil
public class InheritableThreadLocalUtil {
public static final InheritableThreadLocal<String> THREAD_LOCAL = new InheritableThreadLocal<>();
//设置线程需要保存的值
public static void setValue (String str) {
THREAD_LOCAL.set(str);
}
//获取线程中保存的值
public static String getValue() {
return THREAD_LOCAL.get();
}
//移除线程中保存的值
public static void remove() {
THREAD_LOCAL.remove();
}
}
3） TransmittableThreadLocalUtil
public class TransmittableThreadLocalUtil {
public static final TransmittableThreadLocal<String> THREAD_LOCAL = new TransmittableThreadLocal<>();
//设置线程需要保存的值
public static void setValue (String str) {
THREAD_LOCAL.set(str);
}
//获取线程中保存的值
public static String getValue() {
return THREAD_LOCAL.get();
}
//移除线程中保存的值
public static void remove() {
THREAD_LOCAL.remove();
}
}
第一章节请移步
Spring Boot使用ThreadLocal、InheritableThreadLocal、TransmittableThreadLocal -1
其它注意
本文章样例：
工程名：spring-boot-inheritablethreadlocal
GitHub：https://github.com/zzyjb/SpringBootLearning
关于异步服务和线程池请移步
