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