A complete overview of Elasticsearch memory including common problems

Opster Team

Nov 2020

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The following configuration error was detected on node 123...

Description

This error can have a severe impact on your system. It's important to understand that it was caused by...

Recommendation

In order to resolve this issue and prevent it from occurring again, we recommend that you begin by changing the configuration to...

X-PUT curl -H "Content-Type: application/json" [customized recommendation]

Overview

Memory is one of the most critical resources to monitor in Elasticsearch. Elasticsearch runs on JVM and uses heap memory areas for query cache, request cache, accessing lucene segments and storing fielddata for aggregations and sorting.

Common problems and important points

The most common error that arises in Elasticsearch is OutOfMemory error. This error comes when the node is not able to cope up with the required heap size space. To avoid this, you need to closely monitor the heap utilization and garbage collector performance.
As per the most up-to-date best practices you should not allocate more than 50 percent of total RAM to JVM heap size. Starting from Elasticsearch version 5.x onward this can be set using -Xms and -Xmx parameters inside jvm.options configuration file. The defaults are set to 1 GB for both minimum and maximum heap size.
The heap size should not set more than 31 GB in any case to avoid the poor garbage collection.