解决Spring session(redis存储方式)监听导致创建大量redisMessageListenerContailner-X线程问题

/**
 * 用于spring session，防止每次创建一个线程
 * @return
 */
@Bean
public ThreadPoolTaskExecutor springSessionRedisTaskExecutor(){
  ThreadPoolTaskExecutor springSessionRedisTaskExecutor = new ThreadPoolTaskExecutor();
  springSessionRedisTaskExecutor.setCorePoolSize(8);
  springSessionRedisTaskExecutor.setMaxPoolSize(16);
  springSessionRedisTaskExecutor.setKeepAliveSeconds(10);
  springSessionRedisTaskExecutor.setQueueCapacity(1000);
  springSessionRedisTaskExecutor.setThreadNamePrefix("Spring session redis executor thread: ");
  return springSessionRedisTaskExecutor;
}

@Autowired(
  required = false  //该处理监听的线程池不是必须的，如果不自定义默认将使用SimpleAsyncTaskExecutor线程池
)
@Qualifier("springSessionRedisTaskExecutor")
public void setRedisTaskExecutor(Executor redisTaskExecutor) {
  this.redisTaskExecutor = redisTaskExecutor;
}

@Bean
public RedisMessageListenerContainer redisMessageListenerContainer() {
  RedisMessageListenerContainer container = new RedisMessageListenerContainer();
  container.setConnectionFactory(this.redisConnectionFactory);
  if (this.redisTaskExecutor != null) {
    container.setTaskExecutor(this.redisTaskExecutor);
  }
  if (this.redisSubscriptionExecutor != null) {
    container.setSubscriptionExecutor(this.redisSubscriptionExecutor);
  }
  container.addMessageListener(this.sessionRepository(), Arrays.asList(new PatternTopic("__keyevent@*:del"), new PatternTopic("__keyevent@*:expired")));
  container.addMessageListener(this.sessionRepository(), Collections.singletonList(new PatternTopic(this.sessionRepository().getSessionCreatedChannelPrefix() + "*")));
  return container;
}
RedisMessageListenerContainer正是处理监听的类，RedisMessageListenerContainer设置了不为空的redisTaskExecutor，因为spring session默认没有配置该Executor，那RedisMessageListenerContainer在处理监听时怎么使用线程呢？我们接着看RedisMessageListenerContainer的源码：
public void afterPropertiesSet() {
  if (this.taskExecutor == null) {
    this.manageExecutor = true;
    this.taskExecutor = this.createDefaultTaskExecutor();
  }
  if (this.subscriptionExecutor == null) {
    this.subscriptionExecutor = this.taskExecutor;
  }
  this.initialized = true;
}
protected TaskExecutor createDefaultTaskExecutor() {
  String threadNamePrefix = this.beanName != null ? this.beanName + "-" : DEFAULT_THREAD_NAME_PREFIX;
  return new SimpleAsyncTaskExecutor(threadNamePrefix);
}