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Database Connection Pool Tuning: HikariCP, PostgreSQL, and Traffic Spikes

Database connection pools look boring until they take production down. Most backend services do not fail because the database has zero capacity. They fail because the application opens too many connections, holds them to…

Apr 7, 2026·8 min read

#spring boot#hikaricp#postgresql

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Spring Boot Production Readiness Checklist: Timeouts, Pools, Health Checks, and Observability

Spring Boot makes it easy to start a service. Production makes it clear whether the service is actually ready. A production-ready service is not just one that passes unit tests. It has bounded timeouts, sane thread pools…

Apr 7, 20264 min read

#spring boot#production readiness#java

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Java Concurrency Patterns: CompletableFuture, Structured Concurrency, and Thread-Safe Design

Java concurrency has three eras: raw and (Java 1-4), the framework (Java 5+), and the virtual thread/structured concurrency era (Java 21+). Each era's patterns still exist in production codebases. Understanding all th…

Jul 8, 20257 min read

#java#concurrency#completablefuture

Java

Java Memory Management Deep Dive: Heap, GC, and Production Tuning

Java's garbage collector is the single biggest source of unexplained latency spikes in production services. A GC pause of 2 seconds is invisible in most logs but visible to every user who happened to make a request durin…

Jun 13, 20257 min read

#java#jvm#garbage collection

Java

Spring Security OAuth2 and JWT: Production Implementation Guide

Spring Security is one of the most powerful and most misunderstood frameworks in the Java ecosystem. Its flexibility is its strength — and its complexity. Misconfigured security is worse than no security, because it give…

Jun 3, 20257 min read

#spring security#oauth2#jwt

Java

Scaling Spring Boot Applications to Handle 10 Million Daily Active Users

10 million daily active users is not an exotic scale — it's where a successful mid-stage startup or a growing enterprise service lands. At this scale, the things that worked for 100,000 users start breaking in interestin…

May 28, 202510 min read

#spring boot#java#scaling

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Java Profiling and Heap Analysis: Finding Memory Leaks and CPU Bottlenecks

Java applications in production develop performance problems that don't reproduce locally: memory that grows slowly until OOM, GC pauses that spike P99 latency, threads that contend on a lock under load. The difference b…

May 9, 20257 min read

#java#profiling#heap analysis

Java

Thread Pool Exhaustion in Spring Boot: Diagnosis, Prevention, and Recovery

Thread pool exhaustion is one of the most deceptive production failures in Spring Boot services. The service is technically running — JVM process alive, health endpoint returning 200, no OutOfMemoryError in logs — but re…

Apr 8, 20259 min read

#spring boot#java#tomcat

Java

Java Streams API: Advanced Patterns and Performance

Most engineers use Java Streams for map/filter/collect and stop there. The full Streams API is significantly more powerful: custom collectors that aggregate in a single pass, flatMap for flattening nested structures, par…

Mar 21, 20259 min read

#java#streams#functional programming

Java

Java Design Patterns: When to Use Them, When to Avoid Them

Design patterns are solutions to recurring design problems. The mistake most engineers make is pattern-matching: "this code has a factory-like structure, let me add a Factory pattern." The right question is: "what proble…

Mar 15, 202510 min read

#java#design patterns#spring boot

Java

Spring Boot Performance Tuning: From 200 to 2000 RPS

A Spring Boot application that handles 200 RPS on Day 1 often has the same underlying hardware capacity to handle 2000 RPS — the gap is how you use it. Most performance bottlenecks in Java web services follow predictable…

Mar 13, 202513 min read

#spring boot#java#performance

Java

Java GC Tuning: From G1 to ZGC — Eliminating Pause-Time Spikes

Garbage collection pauses are the invisible killer of Java application latency. A service with p99 latency of 20ms can suddenly spike to 500ms because GC paused all threads for a full collection. Understanding GC interna…

Feb 22, 202510 min read

#java#gc#performance

Java

Java 21 Virtual Threads: The End of Reactive Programming Boilerplate

For the past decade, Java developers dealing with high-concurrency IO-bound workloads faced an uncomfortable choice: write readable sequential code that does not scale, or write reactive/async code that scales but is not…

Feb 5, 202512 min read

#java#java21#concurrency

Java

Sync vs Async in Java: CompletableFuture, Reactive Streams, and Virtual Threads

Java has accumulated three distinct paradigms for handling concurrency over the past 15 years: traditional blocking threads, CompletableFuture-based async composition, and reactive programming with Project Reactor/RxJava…

Jan 26, 202511 min read

#java#async#concurrency

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