# Higher CPU usage in cluster than a single node

**URL:** <https://discuss.elastic.co/t/higher-cpu-usage-in-cluster-than-a-single-node/195439>\
**Category:** Elasticsearch\
**Created:** [August 16, 2019, 6:40am UTC](https://discuss.elastic.co/t/higher-cpu-usage-in-cluster-than-a-single-node/195439 "2019-08-16T06:40:11Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![shinmaeng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/shinmaeng/32/85734_2.png) [@shinmaeng](https://discuss.elastic.co/u/shinmaeng)\
**Post date:** [August 16, 2019, 6:40am UTC](https://discuss.elastic.co/t/higher-cpu-usage-in-cluster-than-a-single-node/195439/1 "2019-08-16T06:40:11Z")

</div>

I am operating an Elasticsearch single node and Kibana in a prod to monitor access log and WAS log. But some queries of Kibana dashboard were too late ( about over 7 sec ) to get information into the dashboard. So we are considering to set up 3-nodes Elastic cluster and have installed 3-nodes ES ( 1 master ) in staging servers.

As a result of the test of executing a slow query in staging servers( 3-nodes and single node), although the response time was shorten to 3-4 sec, CPU usage was far higher than a single node. Comparison is table below.

| | response time | CPU usage |
| --- | --- | --- |
| single node | 6 - 7 sec | under 30% |
| 3-node | 3 - 4 sec | all nodes over 50%, even 70-80% |

All servers have 4-core, 16GB and I have set -Xms 2G, -Xmx 2G in a jvm option configure file.  
Both the single node and the cluster have the same indices and 5 primary shards and 1 replica.( So, the indices in the single node have yellow status.. ) The size of each index is about 1 ~ 2 GB.

Since the query has many 'OR' condition, I admit that it is needed to optimize that. But It seems to be weired that all nodes in cluster have high CPU usage about 3 times compared to a single node nevertheless they have the same configuration and spec.

1. Is it normal that CPU usage is high in multiple nodes cluster?
2. Or do I have things to optimize the cluster or change configurations?

Thank you for replies in advance!!

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [September 13, 2019, 6:40am UTC](https://discuss.elastic.co/t/higher-cpu-usage-in-cluster-than-a-single-node/195439/2 "2019-09-13T06:40:26Z")

</div>

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.