基于SpringBoot多线程@Async的使用体验-eolink官网

基于SpringBoot多线程@Async的使用体验

目录多线程@Async的使用体验场景1.线程池配置2.子父线程之间共享一个Request的配置方案3.阻塞主线程，等待所有子线程执行完毕后继续执行主线程1.CountDownLatch2.Future4.多线程共用一个事务异步调用@Async问题1.使用背景2.异步处理方式3.@Async不返回数据4.@Async返回数据5.异常处理

多线程@Async的使用体验

场景

导入：可以将大批量的数据insert操作采用多线程的方式并行执行

第三方服务的接口调用：由于存在个别第三方服务调用比较耗时的场景，此时就可以与自身服务的逻辑并行执行

简而言之：接口中部份业务逻辑可以通过并行的方式来优化接口性能

1.线程池配置

@Configuration

@EnableAsync

public class TaskPoolConfig {

@Bean("taskExecutor") // bean 的名称，默认为首字母小写的方法名

public Executor taskExecutor() {

ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

//核心线程数（CPU核心数+1）

executor.setCorePoolSize(10);

//最大线程数（2*CPU核心数+1）

executor.setMaxPoolSize(20);

//缓冲队列数

executor.setQueueCapacity(200);

//允许线程空闲时间（单位：默认为秒）

executor.setKeepAliveSeconds(60);

//线程池名前缀

executor.setThreadNamePrefix("sub-thread-");

// 增加 TaskDecorator 属性的配置

executor.setTaskDecorator(new ContextDecorator());

// 线程池对拒绝任务的处理策略:CallerRunsPolicy：不在新线程中执行任务，而是由调用者所在的线程来执行

executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());

executor.initialize();

return executor;

}

2.子父线程之间共享一个Request的配置方案

1.实现TaskDecorator接口

/**

* 子线程装饰器

* @author Da Shuai

* @date 2021-06-10 18:28:17

public class SubThreadTaskDecorator implements TaskDecorator {

@Override

public Runnable decorate(Runnable runnable) {

RequestAttributes context = RequestContextHolder.currentRequestAttributes();

return () -> {

try {

RequestContextHolder.setRequestAttributes(context);

runnable.run();

} finally {

RequestContextHolder.resetRequestAttributes();

}

};

}

2.之前的线程池配置加如下代码使其生效

// 增加 TaskDecorator 属性的配置

executor.setTaskDecorator(new ContextDecorator());

3.阻塞主线程，等待所有子线程执行完毕后继续执行主线程

1.CountDownLatch

思路：

实例化CountDownLatch对象，同时传入x（线程数量：这个数量必须等于子线程数量）进行构造

每个子线程执行完毕后会调用countDown()方法

子线程逻辑后方调用await()方法

这样线程计数器为0之前，主线程就一直处于pending状态

主线程逻辑

new Couhttp://ntDownLatch(X)

latch.await()

@Override

@Transactional

public void importExcel(File file) {

CountDownLatch latch = new CountDownLatch(3);

for (int i = 0; i < 3; i++) {

VoteDO voteDO = new VoteDO();

voteDO.setTitle(i + "");

asyncManager.asyncSaveVote(voteDO);

}

//System.out.println(1/0);

try {

latch.await();

} catch (InterruptedException e) {

e.printStackTrace();

}

子线程逻辑

latch.countDown()

@Override

@Async

public void asyncSaveVote(VoteDO voteDO, CountDownLatch latch) {

log.info("当前线程为 {}，休眠10s开始", Thread.currentThread().getName());

try {

Thread.sleep(10000L);

} catch (InterruptedException e) {

e.printStackTrace();

}

log.info("当前线程为 {}，休眠10s结束", Thread.currentThread().getName());

log.info("当前线程为 {}，保存开始", Thread.currentThread().getName());

voteDO.setDesc(Thread.currentThread().getName());

voteDao.insert(voteDO);

latch.countDown();

log.info("当前线程为 {}，保存结束", Thread.currentThread().getName());

}

日志

2021-06-11 16:31:08.653 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : ===============请求内容===============

2021-06-11 16:31:08.653 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : 请求地址:http://localhost:8080/api/import

2021-06-11 16:31:08.653 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : 请求方式:POST

2021-06-11 16:31:08.655 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : 请求类方法:com.zhdj.controller.ImportController.importExcel

2021-06-11 16:31:08.655 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : 请求类方法参数:[org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@42c3f403]

2021-06-11 16:31:08.655 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : ===============请求内容===============

2021-06-11 16:31:08.676 INFO 27516 --- [nio-8080-exec-1] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting...

2021-06-11 16:31:08.894 INFO 27516 --- [nio-8080-exec-1] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed.

2021-06-11 16:31:08.921 INFO 27516 --- [ sub-thread-3] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-3，休眠10s开始

2021-06-11 16:31:08.921 INFO 27516 --- [ sub-thread-1] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-1，休眠10s开始

2021-06-11 16:31:08.921 INFO 27516 --- [ sub-thread-2] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-2，休眠10s开始

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-2] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-2，休眠10s结束

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-3] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-3，休眠10s结束

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-2] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-2，保存开始

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-1] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-1，休眠10s结束

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-3] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-3，保存开始

2021-06-11 16:31:18.921 INFO 27516 --- [ sub-thread-1] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-1，保存开始

2021-06-11 16:31:19.080 DEBUG 27516 --- [ sub-thread-3] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:31:19.080 DEBUG 27516 --- [ sub-thread-1] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:31:19.080 DEBUG 27516 --- [ sub-thread-2] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:31:19.156 DEBUG 27516 --- [ sub-thread-1] com.zhdj.dao.VoteDao.insert : ==> Parameters: 0(String), sub-thread-1(String), 2021-06-11T16:31:19.032(Locahttp://lDateTime), 2021-06-11T16:31:19.037(LocalDateTime)

2021-06-11 16:31:19.156 DEBUG 27516 --- [ sub-thread-3] com.zhdj.dao.VoteDao.insert : ==> Parameters: 2(String), sub-thread-3(String), 2021-06-11T16:31:19.032(LocalDateTime), 2021-06-11T16:31:19.037(LocalDateTime)

2021-06-11 16:31:19.156 DEBUG 27516 --- [ sub-thread-2] com.zhdj.dao.VoteDao.insert : ==> Parameters: 1(String), sub-thread-2(String), 2021-06-11T16:31:19.032(LocalDateTime), 2021-06-11T16:31:19.037(LocalDateTime)

2021-06-11 16:31:19.172 DEBUG 27516 --- [ sub-thread-3] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:31:19.178 DEBUG 27516 --- [ sub-thread-2] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:31:19.187 DEBUG 27516 --- [ sub-thread-1] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:31:19.224 INFO 27516 --- [ sub-thread-3] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-3，保存结束

2021-06-11 16:31:19.224 INFO 27516 --- [ sub-thread-1] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-1，保存结束

2021-06-11 16:31:19.224 INFO 27516 --- [ sub-thread-2] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-2，保存结束

2021-06-11 16:31:19.226 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : --------------返回内容----------------

2021-06-11 16:31:19.328 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : Response内容:null

2021-06-11 16:31:19.328 INFO 27516 --- [nio-8080-exec-1] com.zhdj.config.LogAspect : --------------返回内容----------------

2.Future

思路：

1.子线程逻辑返回Future对象

2.主线程逻辑循环判断每个子线程返回的Future对象isDone()是否为true

主线程逻辑

循环判断future.isDone()是否为true

@Override

@Transactional

public void importExcel(File file) {

List futureList = new ArrayList<>();

for (int i = 0; i < 3; i++) {

VoteDO voteDO = new VoteDO();

voteDO.setTitle(i + "");

Future future = asyncManager.asyncSaveVote(voteDO);

futureList.add(future);

}

//检查所有子线程是否均执行完毕

while (true) {

boolean isAllDone = true;

for (Future future : futureList) {

if (null == future || !future.isDone()) {

isAllDone = false;

}

if (isAllDone) {

log.info("所有子线程执行完毕");

break;

}

子线程逻辑

返回Future对象

@Override

public Future asyncSaveVote(VoteDO voteDO) {

log.info("当前线程为 {}，休眠10s开始", Thread.currentThread().getName());

try {

Thread.sleep(10000L);

} catch (InterruptedException e) {

e.printStackTrace();

}

log.info("当前线程为 {}，休眠10s结束", Thread.currentThread().getName());

log.info("当前线程为 {}，保存开始", Thread.currentThread().getName());

voteDO.setDesc(Thread.currentThread().getName());

voteDao.insert(voteDO);

log.info("当前线程为 {}，保存结束", Thread.currentThread().getName());

//返回需要用AsyncResult类

return new AsyncResult<>(true);

}

日志

2021-06-11 16:42:28.974 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : ===============请求内容===============

2021-06-11 16:42:28.974 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : 请求地址:http://localhost:8080/api/import

2021-06-11 16:42:28.974 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : 请求方式:POST

2021-06-11 16:42:28.975 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : 请求类方法:com.zhdj.controller.ImportController.importExcel

2021-06-11 16:42:28.975 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : 请求类方法参数:[org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@7e23bacc]

2021-06-11 16:42:28.975 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : ===============请求内容===============

2021-06-11 16:42:28.979 INFO 20492 --- [ sub-thread-5] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-5，休眠10s开始

2021-06-11 16:42:28.979 INFO 20492 --- [ sub-thread-4] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-4，休眠10s开始

2021-06-11 16:42:28.979 INFO 20492 --- [ sub-thread-6] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-6，休眠10s开始

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-6] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-6，休眠10s结束

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-4] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-4，休眠10s结束

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-5] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-5，休眠10s结束

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-6] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-6，保存开始

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-5] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-5，保存开始

2021-06-11 16:42:38.980 INFO 20492 --- [ sub-thread-4] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-4，保存开始

2021-06-11 16:42:38.981 DEBUG 20492 --- [ sub-thread-4] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:42:38.981 DEBUG 20492 --- [ sub-thread-5] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:42:38.981 DEBUG 20492 --- [ sub-thread-6] com.zhdj.dao.VoteDao.insert : ==> Preparing: INSERT INTO vote ( title, `desc`, gmt_create, gmt_modified ) VALUES ( ?, ?, ?, ? )

2021-06-11 16:42:38.982 DEBUG 20492 --- [ sub-thread-5] com.zhdj.dao.VoteDao.insert : ==> Parameters: 1(String), sub-thread-5(String), 2021-06-11T16:42:38.980(LocalDateTime), 2021-06-11T16:42:38.981(LocalDateTime)

2021-06-11 16:42:38.982 DEBUG 20492 --- [ sub-thread-4] com.zhdj.dao.VoteDao.insert : ==> Parameters: 0(String), sub-thread-4(String), 2021-06-11T16:42:38.980(LocalDateTime), 2021-06-11T16:42:38.981(LocalDateTime)

2021-06-11 16:42:38.982 DEBUG 20492 --- [ sub-thread-6] com.zhdj.dao.VoteDao.insert : ==> Parameters: 2(String), sub-thread-6(String), 2021-06-11T16:42:38.980(LocalDateTime), 2021-06-11T16:42:38.981(LocalDateTime)

2021-06-11 16:42:38.988 DEBUG 20492 --- [ sub-thread-5] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:42:38.989 INFO 20492 --- [ sub-thread-5] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-5，保存结束

2021-06-11 16:42:38.993 DEBUG 20492 --- [ sub-thread-6] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:42:38.993 INFO 20492 --- [ sub-thread-6] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-6，保存结束

2021-06-11 16:42:39.004 DEBUG 20492 --- [ sub-thread-4] com.zhdj.dao.VoteDao.insert : <== Updates: 1

2021-06-11 16:42:39.005 INFO 20492 --- [ sub-thread-4] com.zhdj.AsyncManagerImpl : 当前线程为 sub-thread-4，保存结束

2021-06-11 16:42:39.005 INFO 20492 --- [nio-8080-exec-2] com.zhdj.service.impl.VoteServiceImpl : 所有子线程执行完毕

2021-06-11 16:42:39.005 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : --------------返回内容----------------

2021-06-11 16:42:39.005 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : Response内容:null

2021-06-11 16:42:39.005 INFO 20492 --- [nio-8080-exec-2] com.zhdj.config.LogAspect : --------------返回内容----------------

4.多线程共用一个事务

暂时无解决方案，这是弊端

异步调用@Async问题

1.使用背景

在项目中，当访问其他人的接口较慢或者做耗时任务时，不想程序一直卡在耗时任务上，想程序能够并行执行，我们可以使用多线程来并行的处理任务，也可以使用spring提供的异步处理方式@Async。

2.异步处理方式

调用之后，不返回任何数据。

调用之后，返回数据，通过Future来获取返回数据

3.@Async不返回数据

使用@EnableAsync启用异步注解

@Configuration

@EnableAsync

@Slf4j

public class AsyncConfig{

}

在异步处理的方法dealNoReturnTask上添加注解@Async

@Component

@Slf4j

public class AsyncTask {

@Async

public void dealNoReturnTask(){

log.info("Thread {} deal No Return Task start", Thread.currentThread().getName());

try {

Thread.sleep(3000);

} catch (InterruptedException e) {

e.printStackTrace();

}

log.info("Thread {} deal No Return Task end at {}", Thread.currentThread().getName(), System.currentTimeMillis());

}

Test测试类：

@SpringBootTest(classes = SpringbootApplication.class)

@RunWith(SpringJUnit4ClassRunner.class)

@Slf4j

public class AsyncTest {

@Autowired

private AsyncTask asyncTask;

@Test

public void testDealNoReturnTask(){

asyncTask.dealNoReturnTask();

try {

log.info("begin to deal other Task!");

Thread.sleep(10000);

} catch (InterruptedException e) {

e.printStackTrace();

}

日志打印结果为：

begin to deal other Task!

AsyncExecutorThread-1 deal No Return Task start

AsyncExecutorThread-1 deal No Return Task end at 1499751227034

从日志中我们可以看出，方法dealNoReturnTask()是异步执行完成的。

dealNoReturnTask()设置sleep 3s是为了模拟耗时任务

testDealNoReturnTask()设置sleep 10s是为了确认异步是否执行完成

4.@Async返回数据

异步调用返回数据，Future表示在未来某个点获取执行结果，返回数据类型可以自定义

@Async

public Future dealHaveReturnTaAyXKtslsk() {

try {

Thread.sleep(3000);

} catch (InterruptedException e) {

e.printStackTrace();

}

jsONObject jsonObject = new JSONObject();

jsonObject.put("thread", Thread.currentThread().getName());

jsonObject.put("time", System.currentTimeMillis());

return new AsyncResult(jsonObject.toJSONString());

}

测试类用isCancelled判断异步任务是否取消，isDone判断任务是否执行结束

@Test

public void testDealHaveReturnTask() throws Exception {

Future future = asyncTask.dealHaveReturnTask();

log.info("begin to deal other Task!");

while (true) {

if(future.isCancelled()){

log.info("deal async task is Cancelled");

break;

}

if (future.isDone() ) {

log.info("deal async task is Done");

log.info("return result is " + future.get());

break;

}

log.info("wait async task to end ...");

Thread.sleep(1000);

}

日志打印如下，我们可以看出任务一直在等待异步任务执行完毕，用future.get()来获取异步任务的返回结果

begin to deal other Task!

wait async task to end ...

deal async task is Done

return result is {"thread":"AsyncExecutorThread-1","time":1499752617330}

5.异常处理

我们可以实现AsyncConfigurer接口，也可以继承AsyncConfigurerSupport类来实现

在方法getAsyncExecutor()中创建线程池的时候，必须使用 executor.initialize()，

不然在调用时会报线程池未初始化的异常。

如果使用threadPoolTaskExecutor()来定义bean，则不需要初始化

@Configuration

@EnableAsync

@Slf4j

public class AsyncConfig implements AsyncConfigurer {

// @Bean

// public ThreadPoolTaskExecutor threadPoolTaskExecutor(){

// ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

// executor.setCorePoolSize(10);

// executor.setMaxPoolSize(100);

// executor.setQueueCapacity(100);

// return executor;

// }

@Override

public Executor getAsyncExecutor() {

ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

executor.setCorePoolSize(10);

executor.setMaxPoolSize(100);

executor.setQueueCapacity(100);

executor.setThreadNamePrefix("AsyncExecutorThread-");

executor.initialize(); //如果不初始化，导致找到不到执行器

return executor;

}

@Override

public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {

return new AsyncExceptionHandler();

}

异步异常处理类：

@Slf4j

public class AsyncExceptionHandler implements AsyncUncaughtExceptionHandler {

@Override

public void handleUncaughtException(Throwable ex, Method method, Object... params) {

log.info("Async method: {} has uncaught exception,params:{}", method.getName(), JSON.toJSONString(params));

if (ex instanceof AsyncException) {

AsyncException asyncException = (AsyncException) ex;

log.info("asyncException:{}",asyncException.getErrorMessage());

}

log.info("Exception :");

ex.printStackTrace();

}

异步处理异常类：

@Data

@AllArgsConstructor

public class AsyncException extends Exception {

private int code;

private String errorMessage;

}

在无返回值的异步调用中，异步处理抛出异常，AsyncExceptionHandler的handleUncaughtException()会捕获指定异常，原有任务还会继续运行，直到结束。

在有返回值的异步调用中，异步处理抛出异常，会直接抛出异常，异步任务结束，原有处理结束执行。

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