applicationTaskExecutor Spring 内置线程池失效

概述

项目中在自定义了两个线程池后有一个线程池注入的地方报错了

java 复制代码

public A(Executor executor) {
        super(executor);
    }

这是一个类注入线程池的方法，名字这里用A替代，一开始项目中并没有使用自定义线程池，有并发需求很多地方都是使用的公共线程池ForkJoinPool, 所以一直没遇到问题，但是我的需求中涉及到集合中的多个元素都要远程调用，于是自定义了线程池：

java 复制代码

@Configuration
@EnableConfigurationProperties({TaskExecutionProperties.class})
public class ThreadPoolConfig {

    // CPU核心数（用于计算默认线程数）
    private static final int CPU_CORES = Runtime.getRuntime().availableProcessors();

    @Bean(name = "r1")
    public Executor r1() {
        // IO密集型
        ThreadPoolTaskExecutor remoteCallExecutor = new ThreadPoolTaskExecutor();
        // 核心线程数
        remoteCallExecutor.setCorePoolSize(Math.min(CPU_CORES, 8));
        // 最大线程数
        remoteCallExecutor.setMaxPoolSize(Math.min(CPU_CORES * 2, 20));
        // 队列长度
        remoteCallExecutor.setQueueCapacity(300);
        // 线程空闲时间
        remoteCallExecutor.setKeepAliveSeconds(60);
        // 线程名字前缀
        remoteCallExecutor.setThreadNamePrefix("remoteCallExecutor-");
        // 线程拒绝策略
        remoteCallExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        // 等待任务的超时时间
        remoteCallExecutor.setAwaitTerminationSeconds(60);
        // 线程初始化
        remoteCallExecutor.initialize();

        return remoteCallExecutor;
    }


@Bean(name = "r2")
    public Executor r2() {
        // IO密集型
        ThreadPoolTaskExecutor remoteCallExecutor = new ThreadPoolTaskExecutor();
        // 核心线程数
        remoteCallExecutor.setCorePoolSize(Math.min(CPU_CORES, 8));
        // 最大线程数
        remoteCallExecutor.setMaxPoolSize(Math.min(CPU_CORES * 2, 20));
        // 队列长度
        remoteCallExecutor.setQueueCapacity(300);
        // 线程空闲时间
        remoteCallExecutor.setKeepAliveSeconds(60);
        // 线程名字前缀
        remoteCallExecutor.setThreadNamePrefix("remoteCallExecutor-");
        // 线程拒绝策略
        remoteCallExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        // 等待任务的超时时间
        remoteCallExecutor.setAwaitTerminationSeconds(60);
        // 线程初始化
        remoteCallExecutor.initialize();

        return remoteCallExecutor;
    }

    

}

这时项目启动，报错：

***************************

APPLICATION FAILED TO START

***************************

Description:

Parameter 0 of constructor in A required a single bean, but 2 were found:

r1: defined by method 'r1' in class path resource $xxx$

r2: defined by method 'r2' in class path resource $xxx$

于是，先去掉了自定义线程池，debug发现没定义线程池之前注入的是一个名为：applicationTaskExecutor 的线程池，于是我加了 @Qualifier("applicationTaskExecutor")之后又打开了自定义线程池，项目启动还是报错

java 复制代码

public A(@Qualifier("applicationTaskExecutor") Executor executor) {
        super(executor);
    }

复制代码

结果还是报错说找不到这个applicationTaskExecutor Bean，很奇怪，于是我创建了一个@PostConstract()标记的方法，打印了所有Executor 类的Bean的名字，发现没有名为 applicationTaskExecutor 的Bean

java 复制代码

 Map<String, Executor> executorMap = applicationContext.getBeansOfType(Executor.class);

原理

于是查找了资料看到了applicationTaskExecutor这个Bean创建的类

java 复制代码

@ConditionalOnClass({ThreadPoolTaskExecutor.class})
@Configuration(
    proxyBeanMethods = false
)
@EnableConfigurationProperties({TaskExecutionProperties.class})
public class TaskExecutionAutoConfiguration {
    public static final String APPLICATION_TASK_EXECUTOR_BEAN_NAME = "applicationTaskExecutor";

    @Bean
    @ConditionalOnMissingBean
    public TaskExecutorBuilder taskExecutorBuilder(TaskExecutionProperties properties, ObjectProvider<TaskExecutorCustomizer> taskExecutorCustomizers, ObjectProvider<TaskDecorator> taskDecorator) {
        TaskExecutionProperties.Pool pool = properties.getPool();
        TaskExecutorBuilder builder = new TaskExecutorBuilder();
        builder = builder.queueCapacity(pool.getQueueCapacity());
        builder = builder.corePoolSize(pool.getCoreSize());
        builder = builder.maxPoolSize(pool.getMaxSize());
        builder = builder.allowCoreThreadTimeOut(pool.isAllowCoreThreadTimeout());
        builder = builder.keepAlive(pool.getKeepAlive());
        TaskExecutionProperties.Shutdown shutdown = properties.getShutdown();
        builder = builder.awaitTermination(shutdown.isAwaitTermination());
        builder = builder.awaitTerminationPeriod(shutdown.getAwaitTerminationPeriod());
        builder = builder.threadNamePrefix(properties.getThreadNamePrefix());
        Stream var10001 = taskExecutorCustomizers.orderedStream();
        var10001.getClass();
        builder = builder.customizers(var10001::iterator);
        builder = builder.taskDecorator((TaskDecorator)taskDecorator.getIfUnique());
        return builder;
    }

    @Lazy
    @Bean(
        name = {"applicationTaskExecutor", "taskExecutor"}
    )
    @ConditionalOnMissingBean({Executor.class})
    public ThreadPoolTaskExecutor applicationTaskExecutor(TaskExecutorBuilder builder) {
        return builder.build();
    }
}

可以看到创建的方法上面标记了 @ConditionalOnMissingBean({Executor.class}) 说明当自定义了线程池之后spring就不会帮助创建内置的线程池了，这也是一个很容易踩坑的地方，一开始我其实只定义了一个线程池，这时候没有报错，A类注入的时候注入的是我自定义的线程池，当时还不知道，当我定义第二个线程池的时候才发现，定义的参数都不同，很可能会出现一些问题。

解决方案

可以自己创建一个与内置线程相同的线程池，命名为applicationTaskExecutor供需要使用的地方使用或者根据需求业务定义合适的线程池来使用

java 复制代码

@Bean("applicationTaskExecutor")
    public ThreadPoolTaskExecutor applicationTaskExecutor(TaskExecutorBuilder builder) {
        return builder.build();
    }

    @Bean
    public TaskExecutorBuilder taskExecutorBuilder(TaskExecutionProperties properties, ObjectProvider<TaskExecutorCustomizer> taskExecutorCustomizers, ObjectProvider<TaskDecorator> taskDecorator) {
        TaskExecutionProperties.Pool pool = properties.getPool();
        TaskExecutorBuilder builder = new TaskExecutorBuilder();
        builder = builder.queueCapacity(pool.getQueueCapacity());
        builder = builder.corePoolSize(pool.getCoreSize());
        builder = builder.maxPoolSize(pool.getMaxSize());
        builder = builder.allowCoreThreadTimeOut(pool.isAllowCoreThreadTimeout());
        builder = builder.keepAlive(pool.getKeepAlive());
        TaskExecutionProperties.Shutdown shutdown = properties.getShutdown();
        builder = builder.awaitTermination(shutdown.isAwaitTermination());
        builder = builder.awaitTerminationPeriod(shutdown.getAwaitTerminationPeriod());
        builder = builder.threadNamePrefix(properties.getThreadNamePrefix());
        Stream<TaskExecutorCustomizer> var10001 = taskExecutorCustomizers.orderedStream();
        var10001.getClass();
        builder = builder.customizers(var10001::iterator);
        builder = builder.taskDecorator((TaskDecorator) taskDecorator.getIfUnique());
        return builder;
    }