Elasticsearch Loaded Client Nodes/Coordinating Nodes



Elasticsearch Loaded Client Nodes/Coordinating Nodes

Opster Team

July 2020, Version: 1.7-8.0


Before you begin reading the explanation below, try running the free ES Health Check-Up get actionable recommendations that can improve Elasticsearch performance and prevent serious incidents. Just 2 minutes to complete and you can check your threadpools, memory, snapshots and many more

What Does it Mean

  • Sometimes you can observe that the CPU and load on some coordinating nodes (client nodes) is higher than others.
  • This can be caused by applications that are not load balancing correctly across the coordinating nodes, and are making all their HTTP calls to just one or some of the nodes.

Possible Effects

A saturated coordinating node could cause an increase in search or indexing response latency, or an increase in write queue/search queue when the cluster is under load (despite there being processing capacity on data nodes). Eventually this could lead to queries timing out.

How to Fix it

You should fix this by putting a load balancer in front of your Elasticsearch nodes, or by including ALL of the nodes in the client application.

es = Elasticsearch(
    ['clientNode1', 'clientNode2','clientNode3'],
    http_auth=('user', 'secret'),
    scheme="https",
    port=443,
)

The above example is how you can load balance across 3 nodes (you should include all the nodes) when using the python client without a load balancer. All of the official Elasticsearch clients use similar arrays in their construction.



About Opster

Opster detects, prevents, optimizes and automates everything needed to run mission-critical Elasticsearch

Find Configuration Errors

Analyze Now