Add configuration properties for configuring Tomcat's keep-alive timeout and max keep-alive requests

[parviz-93]

and maxKeepAliveRequests
See #23539

[wilkinsona]

@parviz-93 Thank you very much for making your first contribution to Spring Boot. Your changes have now been merged along with a small polishing commit.

[parviz-93]

@wilkinsona Thanks a lot for this experience. Thanks a lot for this experience. If there are still such tasks, I am ready to contribute to my favorite framework

[aplatt]

It looks like the keep-alive timeout only worked for HTTP/1.1. The timeout for HTTP/2 was still 20s. This is how I got around it based on a @shunminli example:

@Configuration
public class TomcatCustomizer implements WebServerFactoryCustomizer<TomcatServletWebServerFactory>
{
    @Value("${server.http.keep-alive-timeout:}")
    private int httpKeepAliveTimeout;

    @Value("${server.http2.keep-alive-timeout:}")
    private long http2KeepAliveTimeout;

    private static final Logger log = LoggerFactory.getLogger(TomcatCustomizer.class);

    @Override
    public void customize(TomcatServletWebServerFactory factory) {
        factory.addConnectorCustomizers(connector -> {
            AbstractHttp11Protocol protocol = (AbstractHttp11Protocol) connector.getProtocolHandler();

            int originMaxKeepAliveRequests = protocol.getMaxKeepAliveRequests();
            protocol.setMaxKeepAliveRequests(-1);
            int originKeepAliveTimeout = protocol.getKeepAliveTimeout();
            protocol.setKeepAliveTimeout(httpKeepAliveTimeout);

            log.info(
                    "####################################################################################");
            log.info("#");
            log.info("# TomcatCustomizer HTTP");
            log.info("#");
            log.info("# origin maxKeepAliveRequests {}", originMaxKeepAliveRequests);
            log.info("# custom maxKeepAliveRequests {}", protocol.getMaxKeepAliveRequests());
            log.info("# origin keepalive timeout: {} ms", originKeepAliveTimeout);
            log.info("# keepalive timeout: {} ms", protocol.getKeepAliveTimeout());
            log.info("# connection timeout: {} ms", protocol.getConnectionTimeout());
            log.info("# max connections: {}", protocol.getMaxConnections());
            log.info("#");
            log.info(
                    "####################################################################################");

        });
        factory.addConnectorCustomizers(connector -> {
            Http2Protocol protocol = (Http2Protocol) connector.findUpgradeProtocols()[0];
            long originKeepAliveTimeout = protocol.getKeepAliveTimeout();
            protocol.setKeepAliveTimeout(http2KeepAliveTimeout);

            log.info(
                    "####################################################################################");
            log.info("#");
            log.info("# TomcatCustomizer HTTP/2");
            log.info("#");
            log.info("# origin keepalive timeout: {} ms", originKeepAliveTimeout);
            log.info("# keepalive timeout: {} ms", protocol.getKeepAliveTimeout());
            log.info("#");
            log.info(
                    "####################################################################################");

        });
    }
}

[bclozel]

@aplatt it sounds like these properties should also cover the HTTP/2 protocol. Could you create a new issue for that?

[aplatt]

I created issue #30267