Elasticsearch Index Queue Size Is High in OpenSearch

By Opster Team

Updated: Apr 11, 2023

| 2 min read

In addition to reading this guide, we recommend you run the Elasticsearch Health Check-Up. It will detect issues and improve your Elasticsearch performance by analyzing your shard sizes, threadpools, memory, snapshots, disk watermarks and more.

The Elasticsearch Check-Up is free and requires no installation.

Before you begin reading this guide, we recommend you try running the OpenSearch Error Check-Up which analyzes 2 JSON files to detect many configuration errors.

Index queue size is high is another one of the issues that can be prevented and resolved automatically using AutoOps for OpenSearch. AutoOps will also help you optimize other important settings and processes in OpenSearch to improve performance and ensure high availability for your crucial data. Try it for free.


If the OpenSearch cluster starts to reject indexing requests, there could be a number of causes. Generally it is an indication that one or more nodes cannot keep up with the volume of indexing / delete / update / bulk requests, resulting in a queue building up on that node. Once the indexing queue exceeds the index queue maximum size (as defined here: Threadpools) then the node will start to reject the indexing requests.

How to resolve it

You should check the state of the thread pool to find out whether the indexing rejections are always occurring on the same node, or are spread across all of the nodes.

GET /_cat/thread_pool/index

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