今天ES搜索一直报 Too many request 的错误，详细的错误信息：

    "type": "es_rejected_execution_exception",
    "reason": "rejected execution of org.elasticsearch.transport.TransportService$4@1f9512f on EsThreadPoolExecutor[search, queue capacity = 1000, org.elasticsearch.common.util.concurrent.EsThreadPoolExecutor@c0efba[Running, pool size = 7, active threads = 7, queued tasks = 1000, completed tasks = 573995]]"

从错误信息中推断，ES默认的请求队列容量是1000，类似于IIS应用程序池里的队列长度，超过这个容量后的请求就得不到响应了，因此需要修改ES的queue capacity，以增加产能

使用Postman发送HTTP PUT请求，URL:

    http://localhost:9200/_cluster/settings

Request Body=>raw内容：

    {
        "persistent":{
            "threadpool.search.queue_size":8000
        },
        "transient":{
            "threadpool.search.queue_size":8000
        }
    }