ElasticSearch version: 6.0.0
No of nodes : 3
Operating System : CentOS 7
Client : Low Level Rest Client of java
No of Index : 3
No of Shards per Index : 3
No of Replicas for Shard : 1
Each machine capacity : 32 Cores CPU
**I am want to know No of threads used for single search query and what formula you using .I checked Elastic Search source its telling No of Nodes * No of Shard per Index and below is proof of source code. **
Case 1 : Based on source code it should use max number of threads are 9 (3 Nodes * 3 Shards for Index ) but its showing active threads count 3 only entire cluster.
Case 2: If single search query checking on multiple index(3 ) it that case its showing active threads count 9 only entire cluster.
Above two cases we are tried more than 100 times ,Any of the single cases also we are not seeing those many active threads count or queue or rejected.
For verification purpose we are used _cat/thread_pool/search url.