Elasticsearch+Spring定时任务报错【not be the scheduler thread. Reason: [Blocking operation]】

报错

java.lang.AssertionError: Expected current thread [Thread[scheduler-5,5,main]] to not be the scheduler thread. Reason: [Blocking operation]
	at org.elasticsearch.threadpool.ThreadPool.assertNotScheduleThread(ThreadPool.java:787) ~[elasticsearch-5.2.2.jar:5.2.2]
	at org.elasticsearch.common.util.concurrent.BaseFuture.get(BaseFuture.java:65) ~[elasticsearch-5.2.2.jar:5.2.2]
	at org.elasticsearch.action.support.AdapterActionFuture.actionGet(AdapterActionFuture.java:68) ~[elasticsearch-5.2.2.jar:5.2.2]

原因

代码
client.prepareExists(indexname).execute().actionGet();
而org.elasticsearch.common.util.concurrent.BaseFuture中调用ThreadPool.assertNotScheduleThread(BLOCKING_OP_REASON)保证其不为"schedule"线程(猜想：避免阻塞调度线程？)。

 <task:scheduler id="taskController" pool-size="20"/>

因此修改scheduler为其他名字即可。

解决

重新new一个线程或者修改beanName以改变线程名前缀。

<task:scheduler id="otherName" pool-size="10"/>

ExecutorConfigurationSupport#afterPropertiesSet会保证将beanName作为线程的前缀。

	/**
	 * Set up the ExecutorService.
	 */
	public void initialize() {
		if (logger.isInfoEnabled()) {
			logger.info("Initializing ExecutorService " + (this.beanName != null ? " '" + this.beanName + "'" : ""));
		}
		if (!this.threadNamePrefixSet && this.beanName != null) {
			setThreadNamePrefix(this.beanName + "-");
		}
		this.executor = initializeExecutor(this.threadFactory, this.rejectedExecutionHandler);
	}

为了防止阻塞调度线程，再将代码 actionGet/get添加了超时时间。