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This article explains why multiple independent login systems hurt user experience and security, reviews traditional session mechanisms and their limitations in clustered environments, and then presents two session‑sharing strategies and a complete CAS‑based SSO solution with Java code examples.
This article explains the principles, advantages, and drawbacks of CAS, LongAdder, and AtomicLong in Java, illustrating why Alibaba recommends LongAdder for high‑concurrency counter scenarios, how the ABA problem arises, and how AtomicStampedReference can mitigate it.
This article provides an in‑depth analysis of the Java ConcurrentHashMap implementation, covering its constructor logic, hash‑table sizing, the core put and get operations, element counting with addCount, multi‑threaded resizing via transfer, treeification of bins, removal, computeIfAbsent, and the design choices that forbid null keys and values to simplify concurrency handling.
This article explains the principles, advantages, and drawbacks of Java's AtomicLong and LongAdder counters, describes the CAS operation and its ABA problem, and analyzes why Alibaba recommends LongAdder for high‑concurrency, high‑availability scenarios in distributed systems.
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.
The article explains the Java Memory Model and its core concepts of visibility, atomicity, and ordering, detailing how volatile, synchronized, and final keywords work, the impact of CPU cache and instruction reordering, and low‑level mechanisms such as lock, cmpxchg, and false sharing.
In high‑concurrency Java applications, LongAdder—introduced in JDK 8 and using partitioned cells to reduce contention—generally outperforms the single‑value AtomicLong, which relies on CAS and can cause CPU waste under heavy load, so Alibaba advises LongAdder for scalable distributed counters, though memory usage and workload specifics must be considered.
This article explains the limitations of traditional HTTP session handling, explores session sharing strategies for clustered environments, and demonstrates how to build a single sign‑on solution using CAS and OAuth2 concepts with complete Java code examples for filters, controllers, and login pages.
This article examines typical high‑concurrency scenarios such as payment processing, online ordering, and cross‑bank transfers, introduces the Compare‑and‑Swap (CAS) approach to ensure strong consistency, explains the ABA problem it can cause, and presents application‑level and data‑layer strategies—including versioning and SQL examples—to mitigate it.
This article explains traditional session mechanisms, challenges in clustered environments, and presents solutions such as session replication and centralized storage, then details the design and implementation of a CAS-based Single Sign-On system in Java, including code for user forms, controllers, filters, and configuration.
This article provides a comprehensive guide to Java atomic variables, explaining their core concepts, underlying CAS mechanism, key classes such as AtomicInteger, AtomicLong, AtomicReference, and AtomicBoolean, and demonstrating practical code examples, use‑cases, performance benefits, limitations, and comparisons with traditional lock‑based synchronization.
This article explains the challenges of multiple product logins, reviews traditional session mechanisms, discusses session sharing solutions in clustered environments, and presents a CAS‑based single sign‑on implementation with Java code examples, highlighting differences between CAS and OAuth2 for secure authentication.
This article explains the concept, definitions, and three deployment types of Single Sign-On (SSO), introduces the Central Authentication Service (CAS) mechanism, and details step‑by‑step login and logout processes across multiple web applications, illustrating each flow with diagrams and examples.
This article explores the challenges of maintaining data consistency under high concurrency in distributed systems, reviewing common consistency issues, distributed lock implementations, optimistic and pessimistic strategies, CAS and ABA problems, and practical solutions such as Redis locks, Zookeeper, and transaction protocols.
This article explains the Java volatile keyword, covering its underlying principles, effects on visibility and instruction reordering, appropriate usage scenarios, limitations, and provides a practical code example demonstrating how volatile ensures thread visibility and prevents dead loops in multithreaded programs.
This article explains the fundamentals of Single Sign-On (SSO), why it is needed in distributed systems, details the components and workflow of the CAS (Central Authentication Service) implementation, and outlines common application scenarios such as e‑commerce, enterprise portals, education, and finance.
This article explains the problems of traditional session management in multi‑service environments, introduces session replication and centralized storage (using Redis), and demonstrates a complete CAS‑based single sign‑on solution with Java code examples for user, controller, filter, and configuration components.
This article explains the concept of optimistic locking in concurrent programming, details four common implementation approaches—version number, timestamp, CAS, and serial number—their underlying mechanisms, and outlines typical scenarios where optimistic locks improve data consistency and performance.
The article explains why multiple independent systems hurt user experience, reviews traditional session and cookie based authentication, discusses session sharing problems in clustered environments, and presents centralized Redis storage and CAS‑based single sign‑on solutions with code examples and a comparison to OAuth2.
This article explains the fundamentals of Single Sign‑On (SSO) and OAuth2.0, compares their token‑based authentication mechanisms, details typical implementation flows such as CAS, and clarifies the distinctions among SSO, OAuth2, JWT, Spring Security and Shiro, while also noting related promotional content.