Default number of threads in Spring boot 2.0 reactive webflux configuration

Question

While using Spring 5 reactive webflux with Spring boot 2.0, what's the default number of threads used to handle requests? How can I configure the number of threads used?

score 11 · Accepted Answer · answered Oct 25 '17 at 08:03

11

The default number of threads for request handling is determined by the underlying web server; by default, Spring Boot 2.0 is using Reactor Netty, which is using Netty's defaults (check out the EventLoopGroup documentation for that).

Spring Boot will soon allow you to customize that part (see #10418). In the meantime, you can provide your own ReactiveWebServerFactory bean and change that through the HttpServer configuration options (see this comment).

answered Oct 25 '17 at 08:03

Brian Clozel

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Currently I see `reactor-http-nio-1` in the logs, I use SpringBoot 2.0.0 M6. How can I configure netty to use all cores? – Shadowfax Nov 26 '17 at 04:21

score 8 · Answer 2 · edited Mar 27 '19 at 11:41

Currently, it seems that Spring Webflux 2.0 does not provide the ability to control threads.

Spring Webflux 2.0 is using Reactor-Netty. And ReactorNettyclass provides some configurations.

reactor.netty.ioWorkerCount
reactor.netty.ioSelectCount
reactor.netty.pool.maxConnections
etc

So, You can use it like this.

System.setProperty("reactor.netty.ioWorkerCount", "100");

I hope that Spring Boot will provide a custom configuration.

Default number of threads in Spring boot 2.0 reactive webflux configuration

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