Threadpool.search.queue_size in ELK 5.*.*

Elastic Stack Elasticsearch
1

Hello guys
in elasticsearch 2.3.4 i have problem with limit param : threadpool.search.queue_size.
By default , this size = 1000.
then i change this param: i added next line to elasticsearch configuration file
threadpool.search.queue_size: 100000

Tell me please, how can i set this settings to my cluster with 5.0.2 version?
it's impossible by added new line to configuration file.
I tried set configuration with PUT command.
But this param is not recongnized.
Thanks you a lot.

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The prefix on all thread pool settings has been changed from threadpool to thread_pool in Elasticsearch 5.x.
Hence your queue_size setting would be:

thread_pool.search.queue_size: 100000

For reference: Settings changes | Elasticsearch Guide [5.0] | Elastic

3

Why would you set it so high though?

4

i have been using that cluster for grafana .
earlier i got the next exception:
EsRejectedExecutionException[rejected execution of org.elasticsearch.transport.TransportService$4@24f72ce
8 on EsThreadPoolExecutor[search, queue capacity = 1000, org.elasticsearch.common.util.concurrent.EsThreadPoolExecutor@6ec226f1[Running, pool size = 4, active threads = 4, queued tasks = 1000, completed tasks = 26994]]];
Caused by: EsRejectedExecutionException[rejected execution of org.elasticsearch.transport.TransportService$4@24f72ce8 on EsThreadPoolExecutor[search, queue capacity = 1000, org.elasticsearch.common.uti
l.concurrent.EsThreadPoolExecutor@6ec226f1[Running, pool size = 4, active threads = 4, queued tasks = 1000, completed tasks = 26994]]]

And found next reason and decisions:
Reason:
Elasticsearch has a thread pool and a queue for search per node. A thread pool will have N number of workers ready to handle the requests. When a request comes and if a worker is free , this is handled by the worker. Now by default the number of workers is equal to the number of cores on that CPU. When the workers are full and there are more search requests , the request will go to queue. The size of queue is also limited. Its by default size is say 100 and if there happens more parallel requests than this , then those requests would be rejected as you can see in the error log.
Decision

  1. Increase the size of queue or threadpool - The immediate solution for this would be to increase the size of the search queue. We can also increase the size of threadpool , but then that might badly effect the performance of individual queries. So increasing the queue might be a good idea. But then remember that this queue is memory residential and increasing the queue size too much can result in Out Of Memory issues. You can get more info on the same here.
  2. Increase number of nodes and replicas - Remember each node has its own search threadpool/queue. Also search can happen on primary shard OR replica.

so after increased i didn't have any problems..

Warkolm, do you think that is's very high ?
May be i should inrease little by little ?
example ->10000, 20000 .. ?

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