What's the Max Connection Numbers of TCP Transport Client

Elastic Stack Elasticsearch
1

I am using the Java TransportClient to connect to ElasticSearch.
The code is just like the following demo:

Settings settings;
TransportClient transportClient = new TransportClient(settings);
transportClient.addTransportAddress(
new InetSocketTransportAddress("xxxx", "9300")));

My questions:

  1. I just open one transport client, the connection numbers of the ES server is increased by 42.
    Why just a transport consumes 42 tcp connections?
  2. How many tcp connections can the ES server hold? If I open many transport clients, for example 1000 transport clients, the tcp connection numbers will increase to a large number, can the ES server hold such many tcp connections?
  3. Is there any way to configure the max number of tcp connections for ES server?

Thank you!

2

@whzcl Did you get answers to your questions? I'm even looking for the answers to similar questions?