# How i can increase the thread\_pool.index.size in 6.6.1
**URL:** https://discuss.elastic.co/t/how-i-can-increase-the-thread-pool-index-size-in-6-6-1/202288
**Category:** Elasticsearch
**Created:** [October 4, 2019, 6:35am UTC](https://discuss.elastic.co/t/how-i-can-increase-the-thread-pool-index-size-in-6-6-1/202288 "2019-10-04T06:35:39Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Kamal\_Ambati](https://discuss.elastic.co/u/Kamal_Ambati)
#### Post date: [October 4, 2019, 6:35am UTC](https://discuss.elastic.co/t/how-i-can-increase-the-thread-pool-index-size-in-6-6-1/202288/1 "2019-10-04T06:35:39Z")
Hi
With the reference to Elasticsearch document for[v6.6.1](https://www.elastic.co/guide/en/elasticsearch/reference/6.6/modules-threadpool.html), i am trying to increase the thread\_pool index/write size to number of cores times 5 (4\*5=20)in elasticsearch.yml file and but getting exceptions during startup. Can you please help me out to increase threads size.
[2019-10-04T05:05:55,882][WARN][o.e.b.ElasticsearchUncaughtExceptionHandler] [es1] uncaught exception in thread [main]
org.elasticsearch.bootstrap.StartupException: java.lang.IllegalArgumentException: Failed to parse value [20] for setting [thread\_pool.write.size] must be \<= 5
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:163) ~[elasticsearch-6.6.1.jar:6.6.1]
Elasticsearch yml config:-
thread\_pool:
index:
size: 20
queue\_size: 1000
write:
size: 20
queue\_size: 2000
Thanks,
Kamal
---
### Author:  [@luiz.santos](https://discuss.elastic.co/u/luiz.santos)
#### Post date: [October 11, 2019, 6:57pm UTC](https://discuss.elastic.co/t/how-i-can-increase-the-thread-pool-index-size-in-6-6-1/202288/2 "2019-10-11T18:57:36Z")
Hi @Kamal_Ambati,
From the [docs](https://www.elastic.co/guide/en/elasticsearch/reference/6.6/modules-threadpool.html), the `write` and `index` thread pools are of type `fixed` and the maximum size for this pool is `1 + # of available processors` . So Elasticsearch won't start when using 20 as you only have 4 processors.
As a side comment, changing thread pools are the last resort when it comes to performance optimization.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [November 8, 2019, 6:57pm UTC](https://discuss.elastic.co/t/how-i-can-increase-the-thread-pool-index-size-in-6-6-1/202288/3 "2019-11-08T18:57:36Z")
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