Still Using JPA in Spring Boot? ⚠️ | Spring WebFlux + R2DBC Tutorial 🚀

🔥 Still Using JPA in Spring Boot? It Might Be Slowing You Down!
In this in-depth tutorial, we’ll show you why JPA (Hibernate + JDBC) is not built for reactive performance, and how to build blazing-fast, non-blocking APIs using Spring WebFlux + R2DBC.

We start by understanding the limitations of thread-per-request models (like Tomcat), and how they fail under high concurrency. Then we dive into the reactive architecture powered by Netty, where threads are reused efficiently, making your apps ready for real-time, scalable workloads.

This video covers:

🔄 Blocking vs Non-blocking I/O with live thread visualization

🧵 Why more threads ≠ better performance

⚠️ Why JDBC and JPA can block your reactive flow

🚀 How to stream data in real time with Flux and MediaType.TEXT_EVENT_STREAM

💡 R2DBC explained: The reactive DB driver you need

🧰 Complete Spring Boot setup with Spring WebFlux + Spring Data R2DBC + MySQL

🔍 Reactive Repository (ReactiveCrudRepository) in action

🧪 Thread analysis, backpressure hints, and real-time logs

✅ Bonus: Delay simulation using SQL SLEEP() to prove non-blocking behavior

By the end of this video, you'll have a full-stack, reactive Spring Boot project with a native Netty server and a fully non-blocking DB integration — with zero blocking bottlenecks.

✅ Tech Stack Used:
Spring Boot 3.x

Spring WebFlux

Project Reactor

Spring Data R2DBC

MySQL (Reactive Driver)

IntelliJ IDEA (optional)

Java 17+

📌 Timestamps

00:00 - Layered Architecture in Spring Boot Explained
02:49 - Tomcat’s Thread-per-Request Model (and its Limitations)
05:32 - CPU Cores vs Threads: Why Blocking Hurts Performance
11:02 - How Netty Reuses Threads in Reactive Systems
12:38 - Spring WebFlux & R2DBC: Building Truly Non-blocking APIs
15:41 - Setting Up a Reactive Spring Boot Project (WebFlux + R2DBC)
21:01 - Streaming Data with Flux.just() in WebFlux
23:12 - Real-Time API Responses using MediaType.TEXT_EVENT_STREAM
26:20 - Building a Reactive REST API with Spring Boot
30:05 - What Virtual Threads Can’t Do: Backpressure Explained
32:57 - Connecting a Reactive Spring App to a Database
34:11 - Blocking vs Reactive Drivers: Why JPA Doesn’t Work
36:19 - What is R2DBC? The Non-blocking JDBC Alternative
40:23 - MySQL Integration with Spring Data R2DBC
47:45 - Using ReactiveCrudRepository in Spring
49:09 - Using R2DBC's findAll() to Query the Database
51:09 - Full Flow: Controller → Service → Repository (Reactive Style)
56:05 - Simulating Delays in Reactive DB Calls (Non-blocking Demo)
58:16 - Using Custom Query with SQL Sleep for Latency Simulation
1:02:45 - Real-Time Thread Switching Logs: Reactive Execution Flow
1:07:07 - Comparing Spring Data JPA vs Spring Data R2DBC
1:16:02 - Homework Challenge: Try with PostgreSQL or H2
1:19:50 - Rewriting the Endpoint using Functional Programming Style
1:33:17 - What’s the Default Thread Pool in R2DBC?
1:34:39 - Can This Code Work with Tomcat Instead of Netty?
1:35:56 - Where Should You Use Spring WebFlux in Real Projects?

💼 For More free/paid courses visit
www.seleniumexpress.com

💼 Bonus: Great for Spring Boot Interview Prep!
this video will give you deep insights into modern backend architecture — especially around:

The difference between blocking and non-blocking system
When to choose WebFlux vs traditional MVC
Why JPA fails in reactive scenarios
How R2DBC and Reactive Repositories work under the hood
Real-world examples of threading, performance, and backpressure
Mastering these concepts will help you stand out in interviews for Java backend, Spring Boot, or reactive programming roles.

#springwebflux #springboot

🎓 Related Courses – For reference

📘 Java Streams & Lambda Expressions
   • Stream API in Java : Foundation |  Java 8  

⚡ Reactive Java with Project Reactor
   • Reactive Programming 01 - Java Stream Vs R...  
🔁 Generics in Java Explained
   • From Beginner to Expert:  Why Java Generic...  

🌐 Spring Boot Crash Course
   • Spring Vs Spring Boot - Why Spring Boot ? ...  

▶️ Spring Boot Microservices
   • What the heck is Spring Cloud ? An Introdu...  

▶️ Apache Kafka Essentials
   • Apache Kafka Tutorial for Beginners - Setu...  

▶️ Spring Bootcamp (FREE)
   • Spring Framework 6 - project setup | Sprin...  

▶️ Spring Live Mock Interview
   • Java interview questions and answers for e...  

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For More free/paid courses visit
www.seleniumexpress.com

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