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Coder Trainee

Experienced in Java and Python, we share and learn together. For submissions or collaborations, DM us.

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Latest from Coder Trainee

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Coder Trainee

Jul 9, 2026 · Backend Development

Java Concurrency Deep Dive – Part 8: Real‑World Pitfalls and Post‑mortem

This article reviews common Java concurrency pitfalls—including deadlocks, ThreadLocal memory leaks, Integer‑cache loops, unbounded thread‑pool queues, and swallowed exceptions—illustrates each with code samples, analyzes real production incidents, and provides a concise checklist and tool‑selection guide for safe concurrent programming.

Best PracticesConcurrentHashMapJava

0 likes · 9 min read

Java Concurrency Deep Dive – Part 8: Real‑World Pitfalls and Post‑mortem

Coder Trainee

Jul 8, 2026 · Backend Development

Deep Dive into Java Concurrency: Analyzing the ConcurrentHashMap Source (Part 7)

This article thoroughly examines Java's ConcurrentHashMap by tracing its evolution from JDK 1.5's segment‑lock design to JDK 8's CAS‑plus‑synchronized implementation, detailing internal structures, put/get algorithms, resizing mechanics, performance trade‑offs, and common interview questions.

ConcurrentHashMapJDK7JDK8

0 likes · 12 min read

Deep Dive into Java Concurrency: Analyzing the ConcurrentHashMap Source (Part 7)

Coder Trainee

Jul 7, 2026 · Backend Development

Deep Dive into Java ThreadPoolExecutor: Source Code Analysis (Part 6)

This article provides a thorough, source‑level walkthrough of Java's ThreadPoolExecutor, covering its core design, state machine, seven key parameters, task‑submission flow, worker creation, execution loop, rejection policies, common pool variants, and interview‑ready explanations of the execute() process.

JavaJava ConcurrencyRejectionPolicy

0 likes · 10 min read

Deep Dive into Java ThreadPoolExecutor: Source Code Analysis (Part 6)

Coder Trainee

Jul 6, 2026 · Backend Development

Deep Dive into Java Concurrency: Practical ReentrantLock and Condition Usage

This article thoroughly compares Java's synchronized keyword with ReentrantLock, explains lock implementation details, fairness, interruptibility, timeout, and Condition usage, provides practical code examples and interview tips, and offers guidance on when to choose each synchronization mechanism.

AQSConditionJava

0 likes · 8 min read

Deep Dive into Java Concurrency: Practical ReentrantLock and Condition Usage

Coder Trainee

Jul 5, 2026 · Fundamentals

Deep Dive into Java Concurrency: Inside the AQS Source Code (Part 4)

This article provides a thorough technical walkthrough of Java's AbstractQueuedSynchronizer, covering its core state and CLH queue structures, exclusive and shared lock acquisition/release processes, Condition implementation, and interview-ready explanations of its underlying mechanisms.

AQSAbstractQueuedSynchronizerCondition

0 likes · 8 min read

Deep Dive into Java Concurrency: Inside the AQS Source Code (Part 4)

Coder Trainee

Jul 4, 2026 · Fundamentals

Deep Dive into Java Concurrency (Part 3): The Low‑Level Mechanics of volatile and CAS

This article explains Java's volatile and CAS primitives, detailing volatile's visibility and ordering guarantees, the memory barriers the JVM inserts, CAS's atomic compare‑and‑swap operation, common pitfalls like the ABA problem, and how their combination enables lock‑free thread safety, with code examples and interview tips.

CASJavaVolatile

0 likes · 9 min read

Deep Dive into Java Concurrency (Part 3): The Low‑Level Mechanics of volatile and CAS

Coder Trainee

Jul 4, 2026 · Backend Development

Deep Dive into Java Concurrency: The Source-Level Mechanics of synchronized

This article thoroughly examines Java's synchronized keyword, covering its three usage forms, the underlying bytecode instructions, how lock information is stored in the object header's Mark Word, the step‑by‑step lock upgrade process from no‑lock to heavyweight, and JVM optimizations such as lock elimination and coarsening, providing interview‑ready explanations.

JVMJavaLock

0 likes · 10 min read

Deep Dive into Java Concurrency: The Source-Level Mechanics of synchronized

Coder Trainee

Jul 3, 2026 · Fundamentals

Deep Dive into Java Concurrency Part 1: Understanding the Core via JMM

This article launches a new series on Java concurrency, explaining why concurrent programming is hard due to hardware, OS and compiler effects, detailing the Java Memory Model’s happens‑before rules, memory barriers, volatile semantics, and comparing volatile with synchronized, plus a practical double‑checked locking example.

JavaVolatileconcurrency

0 likes · 8 min read

Deep Dive into Java Concurrency Part 1: Understanding the Core via JMM

Coder Trainee

Jun 29, 2026 · Backend Development

Java Performance Tuning in Practice (Part 6): End-to-End Case Study from Full GC to 200 ms Response

The article walks through a real e‑commerce order service where afternoon spikes caused response times to jump to 2‑3 seconds, Full GC to run every few minutes, and Metaspace to hit 99.9%, then demonstrates step‑by‑step analysis using monitoring, GC logs, jstat, jmap, and heap dumps, fixes a custom class‑loader leak, adjusts JVM flags, and achieves sub‑200 ms latency with no Full GC.

Classloader LeakGCJVM

0 likes · 8 min read

Java Performance Tuning in Practice (Part 6): End-to-End Case Study from Full GC to 200 ms Response

Coder Trainee

Jun 28, 2026 · Fundamentals

Java Performance Tuning Part 5: Hands‑On GC Optimization from G1 to ZGC

This article walks through Java GC tuning by defining low‑latency and high‑throughput goals, comparing major collectors, presenting G1 and ZGC configuration examples, and demonstrating a real‑world payment system case where pause times were reduced from 150‑200 ms to under 50 ms.

G1GCHigh Throughput

0 likes · 8 min read

Java Performance Tuning Part 5: Hands‑On GC Optimization from G1 to ZGC