Where is the callback function executed for searchAsync method

Hi, I'm wondering where the callback function is executed when using searchAsync: Search API | Java REST Client [7.14] | Elastic
Is there some thread pool for the es client?

If you follow the RestClientBuilder class, you see that you can pass a custom ThreadFactoryto the HttpAsyncClientBuilder that is used to start an additional thread.

See https://github.com/elastic/elasticsearch/blob/master/client/rest/src/main/java/org/elasticsearch/client/RestClientBuilder.java#L334

Hope this helps!