Number of force_merge threads

OpenSearch
1

Hi, I have opensearch “2.11.0” and I can’t increase the number of force_merge threads.

GET /_cluster/settings?include_defaults=true say :

    "thread_pool": {
.......,
      "force_merge": {
        "queue_size": "-1",
        "size": "3"
      },

but despite that GET /_cat/thread_pool says:

node1 force_merge                                 1 0 0
node2 force_merge                                 1 0 0

and force_merge takes too long

Index that’s merging also has increased config:

GET /index123/_settings :

        "merge": {
          "scheduler": {
            "max_thread_count": "43",
            "max_merge_count": "50"
          },
          "policy": {
            "floor_segment": "100mb",
            "max_merge_at_once": "40",
            "max_merged_segment": "2gb"
          }
        },

Why there are only 2 forcemerge threads instead of 2*3=6 ?

2

@DmitryP The _cat/thread_pol only says that

  • There is one ongoing force_merge operation. (1)
  • The queue is currently empty. (0)
  • No tasks have been rejected. (0)

If you want to increase the size of the force_merge queue, you can add the below line to opensearch.yml
i.e.

thread_pool.force_merge.queue_size: 100
3

They helped me here
elasticsearch - Number of force_merge threads - Stack Overflow