如果你的项目并发量比较高，想要修改最大线程数、最大连接数等配置信息，可以通过自定义Web 容器的方式，代码如下所示。
@SpringBootApplication(proxyBeanMethods = false)
public class App implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
public static void main(String[] args) {
SpringApplication.run(PetClinicApplication.class, args);
}
@Override
public void customize(ConfigurableServletWebServerFactory factory) {
TomcatServletWebServerFactory f = (TomcatServletWebServerFactory) factory;
f.setProtocol("org.apache.coyote.http11.Http11Nio2Protocol");
f.addConnectorCustomizers(c -> {
Http11NioProtocol protocol = (Http11NioProtocol) c.getProtocolHandler();
protocol.setMaxConnections(200);
protocol.setMaxThreads(200);
protocol.setSelectorTimeout(3000);
protocol.setSessionTimeout(3000);
protocol.setConnectionTimeout(3000);
});
}
}
注意上面的代码，我们设置了它的协议为 org.apache.coyote.http11.Http11Nio2Protocol，意思就是开启了 Nio2。这个参数在 Tomcat 8.0之后才有，开启之后会增加一部分性能。
对比如下（测试项目代码见 spring-petclinic-main）：https://gitee.com/xjjdog/tuning-lagou-res/tree/master/tuning-020/spring-petclinic-main
默认。
[root@localhost wrk2-master]# ./wrk -t2 -c100 -d30s -R2000 http://172.16.1.57:8080/owners?lastName= Running 30s test @ http://172.16.1.57:8080/owners?lastName= 2 threads and 100 connections Thread calibration: mean lat.: 4588.131ms, rate sampling interval: 16277ms Thread calibration: mean lat.: 4647.927ms, rate sampling interval: 16285ms Thread Stats Avg Stdev Max +/- Stdev Latency 16.49s 4.98s 27.34s 63.90% Req/Sec 106.50 1.50 108.00 100.00% 6471 requests in 30.03s, 39.31MB read Socket errors: connect 0, read 0, write 0, timeout 60 Requests/sec: 215.51 Transfer/sec: 1.31MB
[root@localhost wrk2-master]# ./wrk -t2 -c100 -d30s -R2000 http://172.16.1.57:8080/owners?lastName= Running 30s test @ http://172.16.1.57:8080/owners?lastName= 2 threads and 100 connections Thread calibration: mean lat.: 4358.805ms, rate sampling interval: 15835ms Thread calibration: mean lat.: 4622.087ms, rate sampling interval: 16293ms Thread Stats Avg Stdev Max +/- Stdev Latency 17.47s 4.98s 26.90s 57.69% Req/Sec 125.50 2.50 128.00 100.00% 7469 requests in 30.04s, 45.38MB read Socket errors: connect 0, read 0, write 0, timeout 4 Requests/sec: 248.64 Transfer/sec: 1.51MB
你甚至可以将 tomcat 替换成 undertow。undertow 也是一个 Web 容器，更加轻量级一些，占用的内存更少，启动的守护进程也更少，更改方式如下：
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-undertow</artifactId> </dependency>