How to adjust thread pool settings?

Hi guys, so sorry I have to ask this simple question. I want to adjust the thread pool setting of the elasticsearch, but I just cannot figure out how. I have read the documents, but they just give me some command like this:

threadpool:
index:
type: fixed
size: 30

I tried to input these with "curl -XPUT" command, but nothing happend. As there are hardly any examples online, i am really stuck here. Can any of you guys help me out and show me hwo to adjust the index thread size? Very much appreciated. So sorry for asking this simple question.

Problem solved. Thanks for noticing the question guys.

In case someone will look into this in the future, the command is:

curl -XPUT localhost:9200/_cluster/settings -d '
{
"persistent" : {
"threadpool.index.size" : 40
}
}'

Why do you want to adjust the threadpools though?
It's not something we generally recommend.

Hi Mark, for the threadpool, do you recommend to remove the definition of the parameters from yml file at all, so the ES will use the default parameters and dynamically manage them?

thank you