Embedded server concept in Spring Boot - Performance & Optimization

Performance: Embedded server concept

MEDIUM IMPACT

This concept affects the application startup time and runtime resource usage by bundling the server inside the app.

Running a Spring Boot application with an embedded server versus deploying to an external server

Spring Boot

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args); // Embedded Tomcat starts automatically
    }
}

// Application packaged as executable JAR with embedded Tomcat server

Embedded server starts with the app, reducing deployment steps and improving startup consistency.

📈 Performance GainReduces deployment complexity and can improve startup time by avoiding external server boot

Running a Spring Boot application with an embedded server versus deploying to an external server

Spring Boot

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class DemoApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(DemoApplication.class);
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

// Application packaged as a WAR and deployed to an external Tomcat server

Deploying as WAR to an external server requires separate server setup and can delay startup due to server initialization overhead.

📉 Performance CostBlocks startup for several seconds due to external server boot and app deployment

Performance Comparison

Pattern	Startup Time	Memory Usage	Deployment Complexity	Verdict
External server deployment (WAR)	Higher (5-10s+)	Lower (server shared)	Higher (server setup needed)	[! ] OK
Embedded server deployment (executable JAR)	Lower (2-5s)	Higher (server bundled)	Lower (self-contained)	[OK] Good

Rendering Pipeline

The embedded server concept impacts the backend startup and runtime environment rather than browser rendering directly. It affects how fast the server is ready to respond to requests, influencing the Largest Contentful Paint (LCP) indirectly by server response time.

→Server Startup

→Application Initialization

→Request Handling

⚠️ BottleneckServer Startup time due to embedded server initialization

Core Web Vital Affected

LCP

This concept affects the application startup time and runtime resource usage by bundling the server inside the app.

Optimization Tips

1Embedded servers reduce deployment complexity by bundling server and app.

2Startup time may increase slightly due to server initialization inside the app.

3Monitor startup logs and JVM metrics to optimize embedded server performance.

Performance Quiz - 3 Questions

How does using an embedded server in Spring Boot affect application startup time compared to deploying on an external server?

A It increases startup time because the server must start separately

B It has no effect on startup time

C It generally reduces startup time by bundling server and app together

D It delays startup due to network overhead

DevTools: Spring Boot Actuator and JVM monitoring tools

How to check: Enable Spring Boot Actuator endpoints and monitor startup logs; use JVM tools like VisualVM to check memory and CPU usage during startup

What to look for: Look for server startup time in logs and memory footprint; faster startup and stable memory indicate good embedded server performance