Editors Note: This post is part 3 of a 3-part series on tuning Elasticsearch performance. Part 1 can be found here and Part 2 can be found here.
Shard Allocation, Rebalancing and Awareness are very crucial and important from the perspective of preventing any data loss or to prevent the painful Cluster Status: RED (a sign alerting that the cluster is missing some primary shards). Apart from shard allocation, everyone loves to tweak threadpools. For whatever reason, it seems people cannot resist increasing thread counts.
The default threadpool settings in Elasticsearch are very sensible. For all threadpools (except search) the threadcount is set to the number of CPU cores. If we have eight cores, we can be running only eight threads simultaneously. It makes sense to assign only eight threads to any particular threadpool.
In this tutorial, we’ll be focussing on Shard Allocation and Threadpool Configuration settings to keep our cluster’s health green and improve overall performance.