Spring boot embedded jettty thread pool maximum size - spring-boot

Question

I want to configure Thread pool size for my application which is using spring boot embedded jetty server. Below is the code snippet i am using.
I want to know what is the maximum thread pool size I can set for the embedded jetty server and is it the correct way of configuring it?
#Bean
public EmbeddedServletContainerFactory jettyConfigBean() {
JettyEmbeddedServletContainerFactory jef = new JettyEmbeddedServletContainerFactory();
jef.addServerCustomizers(new JettyServerCustomizer() {
public void customize(org.eclipse.jetty.server.Server server) {
final QueuedThreadPool threadPool = server.getBean(QueuedThreadPool.class);
server.setHandler(handlers);
}
});
return jef;
}

Answer 1

Speaking for spring-boot 2.0.0-SNAPSHOT:
This is for jetty and tomcat and undertow configurable via
server.jetty.acceptors
server.tomcat.max-connections
server.undertow.io-threads
See https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#common-application-properties for a complete reference.

Answer 2

The maximum number of threads you can set is dependent on your machine, not so much on the hosting software. If you have a monster machine you can probably have hundreds of threads, whereas a regular laptop would probably only be able to handle tens of threads. You need to tune your configuration by testing. A good way is to setup a load test, for example see if 50 threads with 50 req/sec will crash your service, then check if increasing/decreasing the number of threads will help. You can find the limits of your application and machine with such a technique.
Regarding the correctness of the configuration, you can read this blog post which explains it very well: http://jdpgrailsdev.github.io/blog/2014/10/07/spring_boot_jetty_thread_pool.html

Answer 3

This is what you can do:
While working on newer versions, you need to create a server factory bean in a configuration file. I tested this on Spring Boot version 2.1.6 while the document I referred to is for version 2.3.3
#Bean
public ConfigurableServletWebServerFactory webServerFactory() {
JettyServletWebServerFactory factory = new JettyServletWebServerFactory();
factory.setPort(8080);
factory.setContextPath("/my-app");
QueuedThreadPool threadPool = new QueuedThreadPool();
threadPool.setMinThreads(10);
threadPool.setMaxThreads(100);
threadPool.setIdleTimeout(60000);
factory.setThreadPool(threadPool);
return factory;
}
Following is the link to Spring Docs: customizing-embedded-containers