Optimize HikariCP for Spring Boot to Avoid DB Connection Exhaustion

#Post6 In the previous posts, we built basic REST APIs step by step. But what happens when something goes wrong? 🤔 Example: User not found Invalid input Server error 👉 By default, Spring Boot returns a generic error response. But in real applications, we need proper and meaningful error handling. That’s where Exception Handling comes in 🔥 Instead of handling exceptions in every method, Spring provides a better approach using @ControllerAdvice 👉 It allows us to handle exceptions globally Example: @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(Exception.class) public String handleException(Exception ex) { return ex.getMessage(); } } 💡 Why use this? • Centralized error handling • Cleaner controller code • Better API response Key takeaway: Use global exception handling to manage errors in a clean and scalable way 🚀 In the next post, we will create custom exceptions for better control 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic

🚀 Spring Boot Tip for Faster Applications One simple improvement that can make a big difference in Spring Boot applications is database connection pooling. Instead of opening a new database connection for every request, Spring Boot uses HikariCP by default to manage connections efficiently. Why it matters: ⚡ Faster response times 📉 Reduced database overhead 🔁 Better handling of high traffic A few useful configurations: • maximumPoolSize – controls the number of connections • connectionTimeout – how long a request waits for a connection • idleTimeout – closes unused connections Optimizing database connections is a small change that can significantly improve application performance. Sometimes performance improvements don’t come from complex architecture, but from tuning the fundamentals. #SpringBoot #Java #BackendDevelopment #JavaDeveloper #Microservices #SoftwareEngineering #TechTips

How Spring Boot Handles Requests Internally (Deep Dive) Ever wondered what happens when you hit an API in Spring Boot? 🤔 Here’s the real flow 👇 🔹 DispatcherServlet Acts as the front controller receives all incoming requests 🔹 Handler Mapping Maps the request to the correct controller method 🔹 Controller Layer Handles request & sends response 🔹 Service Layer Contains business logic 🔹 Repository Layer Interacts with database using JPA/Hibernate 🔹 Response Handling Spring converts response into JSON using Jackson 🔹 Exception Handling Handled globally using @ControllerAdvice 💡 Understanding this flow helped me debug issues faster and design better APIs. #Java #SpringBoot #BackendDeveloper #Microservices #RESTAPI #FullStackDeveloper #LearningInPublic

💡 The file upload mistake that would've haunted me in production storing a full URL in your database is a trap. https://lnkd.in/getwKNqc — looks fine. works fine. until you switch storage providers and realize you now have 50,000 rows to update in production. Took me an embarrassing amount of time to figure out the right way: store only the key → users/abc123.jpg keep the base URL in your config combine them at runtime when building responses One env variable change. entire system migrated. database never stores a domain name again. That was just one of three things I got wrong building file uploads this week. The second one: skipping compression. a user uploads a 4MB phone photo, you store a 4MB phone photo. your storage bill is quiet now. it won't be later. compress before upload, not after. a 3MB image should leave your server under 150KB. The third: public storage buckets. if your file URL works forever with no auth, that's not a feature. generate signed URLs with expiry instead. 10 extra lines of code, one less thing to regret. File uploads feel like a solved problem until you actually build one properly. #Java #SpringBoot #BackendDev

When updating data in a Spring Boot API, standard validation can be too restrictive, often requiring all fields to be sent even for minor changes. A more flexible solution is to use @Validated with validation groups. This approach allows you to define separate sets of rules. For example, you can have a "create" group that requires all fields to be present, and a "default" group that only checks the format of fields that are actually provided in the request. In your controller, you then apply the appropriate rule set: the strict rules for creating new items and the flexible rules for updating them. This allows your API to handle both full and partial updates cleanly while reusing the same data object, resulting in more efficient code. #SpringBoot #Java #API #Validation #SoftwareDevelopment

Spent 25 minutes wondering why my Spring Boot API was returning empty response The controller looked fine @GetMapping("/users") public List<User> getUsers() {   return userService.findAll(); } Service was returning data when I debugged But the API response was always empty The problem was the User class had no getters Jackson needs getters to serialize objects to JSON No getters means no fields in the response The fix was adding @Data from Lombok One annotation and everything worked Spring Boot returned the data but Jackson could not read the fields without getters Ever had a bug that made you question everything #Java #SpringBoot #Jackson #Debugging #BackendDevelopment

A single slow Database query almost brought down a production system I worked on. Not because of the query itself, but because it consumed every available thread, leaving nothing for the services that actually mattered. The fix? Bulkhead Semaphore pattern. Isolate your thread pools. Set a queue. Define a fallback. The slides show exactly how. Full Resilience4j docs: https://lnkd.in/dyMxUx_j #java #springboot #backend #resilience4j #softwareengineering

@Service in Spring Boot @Service is used to define the business logic layer in a Spring Boot application. It tells Spring: “This class contains the core logic of the application.” Key idea: • Processes data • Applies business rules • Connects Controller and Repository Works closely with: • @Repository → Fetches data • @RestController → Handles requests In simple terms: @Service → Handles Logic Understanding @Service helps you keep your application clean, organized, and maintainable. #SpringBoot #Java #BackendDevelopment #LearningInPublic

Unlock the full potential of your Spring applications this spring! Virtual threads are here to revolutionize concurrency, allowing millions of I/O-bound requests without blocking. Discover how to harness this power with Spring Boot 3.2, just a single property away. Read the full article to learn more: https://lnkd.in/gQKvdECS #concurrency #Java #Java21 #Performance #SpringBoot

🚨 Fetching all data from DB is a silent performance killer I once saw an API fetching 50,000 records in one go. 💥 Result: High memory usage Slow response Occasional crashes ✅ Fix: Used pagination: Pageable pageable = PageRequest.of(page, size); 💡 Bonus: Added sorting + limit control from API 💡 Takeaway: Never trust frontend to “handle large data” Backend should enforce limits. #Java #SpringBoot #BackendDevelopment #SoftwareEngineering  #Microservices #JPA #RESTAPI  #DeveloperLife #CareerGrowth