Failed to detect hot threads – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch is unable to identify the threads that are consuming the most CPU resources, also known as “hot threads”. This could be due to insufficient system resources, high load, or internal issues within Elasticsearch. To resolve this issue, you can try to reduce the load on your Elasticsearch cluster, increase system resources, or restart the Elasticsearch service. If the problem persists, you may need to investigate further into the internal workings of your Elasticsearch cluster.

This guide will help you check for common problems that cause the log ” failed to detect hot threads ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: admin, threads, node, cluster.

Log Context

Log “failed to detect hot threads” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 try {
 return new NodeHotThreads(clusterService.localNode(); hotThreads.detect());
 } catch (Exception e) {
 throw new ElasticsearchException("failed to detect hot threads"; e);
 }  public static class NodeRequest extends TransportRequest {