1 views collected around this technical thread.
This article explains the main conditions that cause Java objects to be promoted from the young generation to the old generation, covering age thresholds, space guarantees, dynamic age determination, and large‑object allocation rules in HotSpot JVM.
This article walks through a real‑world production case, detailing how to systematically detect, analyze, and resolve severe JVM garbage‑collection pauses in a high‑concurrency Spring Boot microservice, covering resource analysis, JVM flag tuning, G1GC migration, JMX listeners, and GC‑log investigation.
The article shares a personal experience of TP-Link's early campus recruitment and salary expectations, then provides a comprehensive Java backend interview guide covering class‑loader delegation, JVM memory layout, garbage‑collector types, synchronized lock mechanics, and common Redis cache pitfalls with practical solutions.
JVM’s generational garbage collection divides the heap into young and old generations, using two Survivor spaces to incrementally age objects, apply a copying algorithm, reduce fragmentation, improve memory utilization, and accelerate short‑lived object reclamation, ultimately enhancing overall GC performance.
This article explains how Azul's CRaC and ReadyNow technologies differ in approach to accelerating Java application startup, detailing the Java launch process, optimization phases, implementation requirements, and a side‑by‑side comparison of their benefits and trade‑offs.
This article explains Java's ClassLoader architecture, the parent delegation model, the three phases of class loading, dynamic loading and binding mechanisms, and demonstrates how to inspect object layout using the JOL tool, providing code examples and practical insights for JVM internals.
This article details how replacing Java's native double parsing with the Ryu and FastFloat algorithms, alongside JVM GC tuning, dramatically reduces CPU usage and latency in backend services, offering practical code examples, benchmark results, and actionable optimization strategies.
This article explains Java's lock mechanisms—including synchronized, ReentrantLock, and their JVM implementations—covers lock classifications, memory barriers, CAS, and compares them with Kotlin coroutine synchronization tools like Mutex, providing code examples and practical guidance for safe concurrent programming.
This guide explains how to launch Java processes from the command line, details key JVM tuning flags such as -X and -XX options, describes garbage collection algorithms, reference strengths, and stop‑the‑world pauses, providing practical examples and diagrams to help developers optimize memory usage and performance.
This tutorial explains the differences between Java's System.exit() and Runtime.getRuntime().halt(), detailing their shutdown sequences, impact on shutdown hooks and finalizers, providing code examples and test cases, and offering guidance on when to use each method safely.
The article explains how to achieve graceful shutdown of Spring Boot services by handling Linux kill signals, registering JVM shutdown hooks, and exposing an Actuator REST endpoint that safely releases resources, stops beans, and terminates the JVM without data loss.
This article introduces the SootUp library, explains how to configure its Maven dependencies, describes the Jimple intermediate representation, and demonstrates how to use SootUp's API to analyze Java source code, bytecode, and method bodies through a series of code examples.
This article uses real‑world analogies to dissect the three core challenges of Java concurrency—ordering, visibility, and atomicity—and explains how hardware instructions, JVM mechanisms, and Java SDK tools such as locks, CAS, and waiting/notification utilities provide efficient solutions.
This article humorously introduces a common interview scenario and then provides a comprehensive overview of JVM garbage collection, covering memory regions, GC roots, collector types like ParNew, G1, CMS, tuning parameters, code examples, and practical tips for diagnosing and optimizing GC behavior.
This article explains the concept of Java's Runtime.addShutdownHook, details its underlying implementation in the Runtime and ApplicationShutdownHooks classes, demonstrates usage with code examples, discusses typical application scenarios, potential risks of long‑running hooks, and provides best‑practice recommendations for safe JVM shutdown handling.
The article recounts a McDonald's China backend interview, explaining IoC/DI concepts, MyBatis benefits, JVM garbage‑collection and memory layout, MySQL engine differences, concurrency locking strategies, RPC advantages over HTTP, HTTPS basics, essential Docker/Kubernetes commands, and a typical Git workflow.
This article details a step‑by‑step experiment using SpringBoot 2.5.4 and JMeter to quantify how much heap memory a single HTTP or RPC request consumes, analyzes GC logs, presents code snippets for the test endpoints, and discusses the impact of logging and payload size on memory usage.
This article explains why the JVM throws java.lang.OutOfMemoryError: GC overhead limit exceeded, outlines common causes such as traffic spikes, memory leaks, insufficient heap and inefficient GC, and provides practical solutions and debugging steps to diagnose and fix the issue.
java.lang.OutOfMemoryError: Requested array size exceeds VM limit occurs when a Java program attempts to allocate an array larger than the JVM's available heap, and can be mitigated by increasing heap size, optimizing code, or processing data in smaller batches.
The article presents a Spring Boot experiment measuring per‑request heap memory usage for HTTP and RPC calls, details the JMeter test setup, analyzes GC logs, reports findings such as ~34KB per HTTP request and 0.5‑1MB per RPC request, offers optimization recommendations, and also includes promotional material for AI‑related products.