Java Articles | Backend Study Lab

Java Aug 19, 2026 4 min read

JVM Profiling and JFR for Production Backends

Use Java 25 Flight Recorder to investigate CPU, allocation, GC, locks, I/O, and virtual threads without overstating profile evidence.

Java Aug 19, 2026 5 min read

Evidence-Based JVM Tuning and Capacity Verification

Turn JVM performance hypotheses into controlled canary changes with representative load, rollback, resource budgets, and user-outcome verification.

Java Aug 19, 2026 5 min read

G1 Garbage Collector Diagnosis and Tuning

Diagnose Java 25 G1 young, marking, mixed, evacuation, and humongous-object behavior before making minimal evidence-backed tuning changes.

Java Aug 19, 2026 4 min read

Java Heap Dumps and Memory Leak Analysis

Use Java 25 class histograms and heap dumps to test retention and memory-leak hypotheses while controlling pause, disk, and data exposure.

Java Aug 19, 2026 5 min read

JVM Garbage Collection Logs and Pause Diagnosis Explained

Read Java 25 garbage collection logs to distinguish allocation pressure, live-set growth, concurrent work, pauses, and Full GC safely.

Java Aug 19, 2026 5 min read

JVM JIT, Code Cache, and Warmup Diagnosis

Diagnose Java 25 tiered compilation, compilation queues, deoptimization, code cache pressure, warmup, JFR, and AOT profile boundaries.

Java Aug 19, 2026 4 min read

JVM Native Memory, Metaspace, and Container OOM Diagnosis

Separate Java heap, HotSpot native memory, metaspace, buffers, stacks, RSS, and container OOM evidence with Java 25 NMT.

Java Aug 19, 2026 4 min read

JVM Thread Dumps, Safepoints, and CPU Saturation Diagnosis

Diagnose Java 25 platform and virtual threads, locks, safepoints, CPU saturation, pinning, and dependency waits with bounded evidence.

Java Aug 19, 2026 5 min read

Production JVM Performance Diagnostics Explained

Diagnose production JVM performance from user impact through CPU, garbage collection, memory, threads, containers, and durable outcomes.

Java Aug 19, 2026 5 min read

ZGC Low-Latency Garbage Collection Diagnosis and Tuning

Diagnose generational ZGC allocation headroom, concurrent work, stalls, heap sizing, and latency-throughput tradeoffs on Java 25.

Java Aug 18, 2026 4 min read

CompletableFuture Composition, Errors, and Timeouts

Compose Java CompletableFuture stages deliberately across executors, failures, timeouts, cancellation, context, and external side-effect boundaries.

Java Aug 18, 2026 5 min read

Java Concurrency for Backend Systems Explained

Build a practical model of tasks, threads, shared state, race conditions, thread safety, and bounded concurrency in Java backend services.

Java Aug 18, 2026 6 min read

Java Concurrency Budget Lab: Queues, Virtual Threads, and Cancellation

Run six deterministic Java concurrency scenarios to compare fixed pools, virtual threads, resource guards, deadlines, and cooperative cancellation.

Java Aug 18, 2026 4 min read

ExecutorService, Thread Pools, and Work Queues in Java

Design Java executors around admission, worker, queue, rejection, shutdown, and downstream capacity instead of treating threads as free throughput.

Java Aug 18, 2026 4 min read

Java Interruption, Cancellation, and Deadlines Explained

Propagate Java interruption and request deadlines cooperatively across executors, blocking calls, cleanup, Spring boundaries, and durable effects.

Java Aug 18, 2026 4 min read

Java Memory Model, Visibility, and Happens-Before Explained

Understand atomicity, visibility, ordering, data races, volatile fields, safe publication, and happens-before reasoning in Java backend code.

Java Aug 18, 2026 4 min read

Scoped Values and Structured Concurrency in Modern Java

Separate Java 25 Scoped Values from JDK 26 preview Structured Concurrency and reason about bounded context, task lifetime, failure, and cancellation.

Java Aug 18, 2026 5 min read

Java Virtual Threads for Backend Services

Use Java 21 virtual threads for blocking backend tasks while keeping CPU, connection pools, downstream limits, context, and pinning explicit.

Java Aug 18, 2026 5 min read

Production Java Concurrency Troubleshooting

Diagnose Java thread starvation, unbounded queues, lock contention, virtual-thread pinning, downstream overload, and failed cancellation with evidence.

Java Aug 18, 2026 5 min read

synchronized, Locks, and Atomic Variables in Java

Compare Java monitors, ReentrantLock, CAS, atomic variables, lock scope, fairness, and compound invariants through backend examples.

Backend Aug 5, 2026 10 min read

Production Spring Boot Backend Systems Explained

Build a production-minded Spring Boot order service by separating HTTP, application, data, security, configuration, operations, testing, and incident-recovery layers.

Backend Aug 5, 2026 10 min read

Spring Boot Exception Handling Explained

Design safe Spring Boot error responses with ProblemDetail and RFC 9457 while respecting MVC, filter, security, async, and committed-response boundaries.

Backend Aug 5, 2026 11 min read

Spring Boot Configuration Properties, Profiles, and Secrets Explained

Use typed Spring Boot configuration, deliberate property precedence, environment profiles, secret injection, and drift evidence without exposing operational control planes.

Backend Aug 5, 2026 10 min read

Spring Boot Request Validation Explained

Separate Spring Boot request-shape validation from authorization and concurrency-safe business invariants, including nested DTO and collection validation.

Backend Aug 5, 2026 11 min read

Spring Data JPA Query Performance Explained

Diagnose Spring Data JPA performance with query, SQL, plan, row, pool-wait, and user-latency evidence instead of relying on fetch-strategy folklore.

Backend Aug 5, 2026 11 min read

Spring Boot Integration Testing with Testcontainers Explained

Use Spring test slices, full-context contracts, Testcontainers PostgreSQL, migrations, security, and failure injection without overstating production equivalence.

Backend Aug 5, 2026 12 min read

Spring Service Layers and Transaction Boundaries Explained

Design Spring application services and transactions that preserve local order invariants without hiding proxy, rollback, thread, remote-call, or side-effect boundaries.

Security Jul 25, 2026 7 min read

API Request Signing Explained

Design HMAC API request signing in Java and Node.js with canonical requests, timestamps, nonces, replay defense, rotation, tests, and failure handling.

Algorithms Jul 25, 2026 7 min read

Graph Traversal: BFS vs DFS

Compare breadth-first and depth-first graph traversal, choose the right strategy, and implement safe iterative Java versions with complexity and tests.

Algorithms Jul 25, 2026 7 min read

Heap Patterns Explained

Recognize heap patterns for top K, kth elements, streaming medians, k-way merge, and scheduling with safe Java PriorityQueue examples.

Algorithms Jul 25, 2026 6 min read

Merge Intervals Explained

Learn the merge intervals pattern, endpoint semantics, sorting invariants, Java implementation, complexity, edge cases, and scheduling variants.

Algorithms Jul 25, 2026 7 min read

Monotonic Stack Explained

Learn how monotonic stacks solve next-greater, stock-span, temperature, and histogram problems in linear time with practical Java examples.

Java Jul 1, 2026 5 min read

HashMap Collision Handling Explained

Learn how HashMap collision handling works in Java, including buckets, hashCode, equals, tree bins, load factor, bad keys, and performance.

Java Jul 1, 2026 5 min read

Java equals and hashCode Explained

Learn Java equals and hashCode contracts, why they matter for HashMap and HashSet, common mistakes, records, mutability, and testing.

Algorithms Jul 1, 2026 4 min read

Prefix Sum Algorithm Explained

Learn prefix sums with Java examples, range-sum queries, subarray patterns, difference arrays, complexity, and when preprocessing is worth it.

Algorithms Jul 1, 2026 5 min read

Sliding Window Algorithm Explained

Learn the sliding window algorithm pattern with Java examples, fixed windows, variable windows, two pointers, complexity, and common mistakes.

Algorithms Jul 1, 2026 5 min read

Two Pointers Algorithm Explained

Learn the two pointers algorithm pattern with Java examples for sorted arrays, pairs, partitions, linked lists, complexity, and common mistakes.

Algorithms Jun 28, 2026 4 min read

Binary Search Explained

Learn how binary search works, when it applies, common off-by-one mistakes, and how to implement iterative binary search in Java.

Java May 10, 2026 6 min read

Time Complexity of Java Collections

A practical reference for Java collection time complexity, including ArrayList, LinkedList, HashMap, TreeMap, HashSet, and PriorityQueue.

Java Mar 15, 2026 4 min read

ConcurrentHashMap Explained

A practical explanation of ConcurrentHashMap in Java, including thread safety, atomic methods, iteration behavior, and common mistakes.

Java Mar 8, 2026 4 min read

HashMap Load Factor Explained

Learn what HashMap load factor means in Java, how it affects resizing, memory usage, collision risk, and lookup performance.

Java Mar 1, 2026 4 min read

ArrayList vs LinkedList in Java

Compare ArrayList and LinkedList in Java by access patterns, insertion cost, memory overhead, and practical backend usage.