# What's the Max Connection Numbers of TCP Transport Client

**URL:** <https://discuss.elastic.co/t/whats-the-max-connection-numbers-of-tcp-transport-client/46325>\
**Category:** Elasticsearch\
**Created:** [April 5, 2016, 5:12am UTC](https://discuss.elastic.co/t/whats-the-max-connection-numbers-of-tcp-transport-client/46325 "2016-04-05T05:12:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![whzcl](https://avatars.discourse-cdn.com/v4/letter/w/eb8c5e/32.png) [@whzcl](https://discuss.elastic.co/u/whzcl)\
**Post date:** [April 5, 2016, 5:12am UTC](https://discuss.elastic.co/t/whats-the-max-connection-numbers-of-tcp-transport-client/46325/1 "2016-04-05T05:12:05Z")

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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!

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**Author:** ![Utkarsh\_Pyne](https://avatars.discourse-cdn.com/v4/letter/u/a587f6/32.png) [@Utkarsh\_Pyne](https://discuss.elastic.co/u/Utkarsh_Pyne)\
**Post date:** [May 16, 2017, 7:53am UTC](https://discuss.elastic.co/t/whats-the-max-connection-numbers-of-tcp-transport-client/46325/2 "2017-05-16T07:53:39Z")

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

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 10:00pm UTC](https://discuss.elastic.co/t/whats-the-max-connection-numbers-of-tcp-transport-client/46325/3 "2017-07-05T22:00:23Z")

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