• Java Queues — A Detailed analysis of Queues

  • Non-blocking queue: ConcurrentLinkedQueue(unbounded thread safety), CAS mechanism (compareAndSwapObject atomic operation).
  • Block queues: ArrayBlockingQueue(bounded), LinkedBlockingQueue (unbounded), DelayQueue, PriorityBlockingQueue (lock mechanism); Use ReentrantLock to lock.

• LinkedList, ConcurrentLinkedQueue, and LinkedBlockingQueue

Each node has a maximum of two leaf nodes.

• Binary tree

• “Graphical Sorting Algorithm (3) heap Sorting”
  • Sorting is the process of building the maximum heap: each node has a value greater than or equal to its left and right children, and the top element is the maximum.

KMP: The core principle of Knuth-Morris-Pratt algorithm (KMP for short) is to use a “partial match table” to skip the already matched elements.

• “KMP Algorithm for String Matching”

• 40 Java Multithreading Problems

• Database Transaction ACID Characteristics

• Classification of Locks in Java

  • These include synchronized, ReentrantLock, and ReadWriteLock.

• AQS in Java Concurrency

• Semaphore in Java

  • Quantity control
  • If acquire is used for application, block if do not apply; Release with release.

• Mutex vs Semaphore in Java Development

  • To put it simply, Mutex is exclusive, and only one can get the resource. Semaphore is also exclusive, but can define multiple objects that can get the resource.

• Fundamentals of Operating Systems — Principles, Types, and Structures of Operating systems

A typical CPU has a three-level cache, which is faster and smaller the closer it is to the core. L1 32K, L2 256K, L3 12M. The memory speed takes 200 CPU cycles and the CPU cache takes 1 CPU cycle.

• Understanding CPU Caching and Pseudo-sharing from a Java Perspective

• The Life cycle of threads and State Transitions

• Six Principles of Design Patterns
  • Open closed principle: Open for extension, closed for modification, use abstract classes and interfaces.
  • Richter’s substitution principle: Base classes can be replaced by subclasses, using abstract class inheritance, not concrete class inheritance.
  • The dependency inversion principle: Rely on the abstract, not the concrete, program for the interface, not the implementation.
  • Interface isolation principle: It is better to use multiple isolated interfaces than to use a single interface, and establish a minimum interface.
  • Demeter’s Law: a software entity should interact with as few other entities as possible, establishing connections through intermediate classes.
  • Rule of composite reuse: use composition/aggregation rather than inheritance whenever possible.

• MVC Pattern
  • Model – View – Controller

• Cultivation of Tencent Business System Monitoring

  • Monitoring methods: active, passive and by-pass (such as public opinion monitoring)
  • Monitoring types: basic monitoring, server monitoring, client monitoring, monitoring, and client monitoring
  • Monitoring objectives: complete, block and accurate
  • Core indicators: Request volume, success rate, time

• Open Source or Commercial? Review of Top 10 Cloud Operation and Maintenance Monitoring Tools

  • Zabbix, Nagios, Ganglia, Zenoss, Open-Falcon, Monitor Treasure, 360 website service monitoring, Ali Cloud Monitoring, Baidu Cloud Observation, Little Bee website monitoring, etc.

• Monitoring and Alarm System Construction and Secondary Development Experience

Command line monitoring tool

• Common Command Line Monitoring Tool

  • Top, SAR, TSAR, NLOAD

• 20 Command Line Tools to Monitor Linux System Performance

• JPS, JStack, JMAP, JHAT, Jstat, Hprof

• The Definitive Guide to Ansible Chinese
• Practical Examples of Ansible Basic Configuration and Enterprise Projects

• Deep Reading – TDD (Test Driven Development)
  • Coding functional code based on test cases is a core practice of XP (Extreme Programming).
  • Benefits: focus on one point at a time, reduce the burden of thinking; Responding to changing requirements or improving code design; Clarify requirements in advance; Quick feedback;

• A few images to help you Understand the basics of Docker and a quick Start
• Docker Core Technology and Implementation Principle
• Docker Tutorial

• Overview of OpenStack Architecture

• Detailed Explanation of TOMCAT Principle and Request Process

• Detailed Principles of the Tomcat Server

• Tomcat System Architecture and Design Patterns, Part 1: How it Works

• Four Diagrams to Guide you to The Tomcat System Architecture

• JBoss vs. Tomcat: Choosing A Java Application Server

  • Tomcat is a lightweight Serverlet container that does not implement all JEE features (such as persistence and transactions), but can be replaced by other components, such as Srping.
  • Jboss implements all JEE features. The software is free and open source, and documentation is charged.

• Memcached Tutorial

• Understanding Memcached in depth

  • Use multiplexing to improve concurrency.
  • Slab allocation algorithm: memcached allocates memory space to a slab. The default value is 1MB. After a Slab is allocated, the Slab is divided into chunks of the same size. Chunk is the memory space for caching records, and the size of chunk increases by 1.25 times by default. The advantage is that it does not frequently apply for memory, which improves I/O efficiency. The disadvantage is that there will be a certain amount of memory waste.

• How Memcached Software Works

• Memcache Technology Sharing: Introduction, Use, Storage, Algorithm, Optimization, Hit Ratio

• The difference between Add, Set and Replace in memcache

  • The difference is that the return value is true and false when the key is present or absent.

• Full Anatomy of Memcached

Several storage engines:

• MDB, fully memory, can be used to store data such as sessions.
• Rdb (similar to Redis), lightweight, eliminates operations like AOF, and supports Restfull operations
• LevelDB (LevelDB storage engine), persistent storage, LDB as RDB persistence, Google implementation, relatively efficient, based on the log-Structured Merge Tree (LSM) algorithm, now modify data in memory, When a certain amount of data is written to the disk together with the old data summarized in memory, the data is then written to the disk for more efficient storage.
• Tair uses shared memory to store data, and if the service fails (not the server), the data remains after the service is restarted.

** SPI ** TODO

• website

• “Build an ELKB Log Collection System from scratch”
• Building a Simple Log Collection and Analysis System with ELK
• Log Collection System – Exploration

Servlet 3.0 asynchrony features can be used to configure central clients

• Servlet3.0 new features — asynchronous processing

• Hessian Principle Analysis Binary-RPC; Not just serialization

• MySQL InnoDB index principle

• MySQL Storage Engine — Difference between MyISAM and InnoDB

  • The main difference between the two types is that Innodb supports transaction processing and foreign keys and row-level locking

• The Difference between MyISam and InnoDB Index Implementation

• MySQL clustered index/unclustered index
• MyISAM and InnoDB index Implementation

MyISAM is non-aggregation, InnoDB is aggregation

• Directing a tutorial
• Advantages and Disadvantages of Mongodb over Relational Databases
  • Advantages: Weak consistency (final consistency), better ensure user access speed; Built-in GridFS to support large storage capacity; Schema-less database, no predefined structure; Built-in Sharding. Compared with other NoSQL, third-party support is richer; Excellent performance;
  • Disadvantages: mongodb does not support transaction operations; Mongodb occupies too much space; MongoDB does not have as mature a maintenance tool as MySQL, which is noteworthy for both development and IT operations.

• Inverted Indexing: An Introduction to Search Engines

• 15 days of Performance optimization, 5 aspects of tuning Experience

  • Code level, business level, database level, server level, front-end optimization.

• Aspects of System Performance Optimization

• What Hadoop is and What It Does in Plain English
• “The Most detailed Hadoop Environment Setup ever”

• Common Symmetric Encryption Algorithms
  • DES, 3DES, Blowfish, AES
  • DES uses 56-bit keys, Blowfish uses varied-length keys of 1 to 448 bits, and AES 128,192 and 256-bit keys.
  • DES secret key is too short (only 56 bits) algorithm has been replaced by AES, and AES has hardware acceleration, performance is very good.

TODO

TODO

• Organizational Role-based Permission Design
• Overview of The Authority System and RBAC Model
• “Detailed case Analysis of Spring integrating Shiro to do Permission Control Module”

• Single Sign-on Principle and Simple Implementation

• CAS single sign-on framework

• Choice of Open Source Agreements

• Log4j In Detail
• Log4j2 Practical Usage Details
• Log4j1,Logback, and Log4j2 Performance Test Comparison
  • Log4J provides excellent asynchronous log performance.

MyBatis:

• Mybatis Cache mechanism details

  • Level 1 cache is SqlSession level cache. Cached data is valid only in SqlSession
  • Level 2 cache is mapper level cache. The same namespace shares this cache, so it shares SqlSession. Use the LRU mechanism to clear the cache, enabled by the cacheEnabled parameter.

• MyBatis Code Generator

Spring Boot

• The official website
• Spring Boot Basics tutorial

Spring Cloud

• Spring Boot Chinese index station
• Spring Cloud Chinese documentation
• Spring Cloud Basics tutorial

• Top 10 Extensible Architectures for Architects to Know

  • In summary, the common patterns are distribution, caching, and asynchronous processing.

• Data Sharding for Scalable Design

  • Horizontal segmentation + vertical segmentation
  • Sharding with middleware such as MySQL Proxy.
  • Use sharding strategy for segmentation, such as module by ID.

• How to Achieve scalable Large-scale Web Architecture

  • Distributed services + message queues.

• Technical Architecture of Large Websites (vii) — Scalability Architecture of Websites

• Never Lost! How to Implement Service discovery in microservices Architecture?

  • Client service discovery mode: The client queries the registry directly and is responsible for load balancing. Eureka takes this approach.
  • Server service discovery mode: The client queries service instances through load balancing.

• Comparison of SpringCloud Service Registries :Consul vs Zookeeper vs Etcd vs Eureka

  • CAP Support: Consul (CA), ZooKeeper (CP), ETCD (CP), and Euerka (AP)
  • The author believes that Consul currently supports Spring Cloud well.

• Zookeeper-based Service Registration and Discovery

  • Advantages: Simple API, Pinterest, Airbnb in use, multi-language, through watcher mechanism to achieve configuration PUSH, can quickly respond to configuration changes.

• From Distributed Consistency to CAP Theory and BASE Theory
  • Consistency classification: strong consistency (immediate consistency); Weak consistency (which can be achieved in unit time, such as seconds); Final agreement (weak agreement, final agreement within a given period of time)
  • CAP: Consistency, availability, and fault tolerance of partitions (due to network failures)
  • BASE: Basically Available, Soft state, and Eventually consistent
  • The core idea of BASE theory is that even if strong consistency cannot be achieved, each application can adopt appropriate ways to achieve the final consistency of the system according to its own business characteristics.

• Distributed Series of articles — Principle and Derivation of Paxos Algorithm
• Fast Paxos–>Zookeeper Analysis
• [Distributed] Zookeeper and Paxos

• Summary of Generating Globally Unique ids in Highly Concurrent Distributed Systems

  • Twitter solution (Snowflake algorithm) : 41-bit timestamp + 10-bit machine id (IP, server name, etc.) + 12-bit serial number (local counter)
  • Flicker solution: MySQL increment ID + “REPLACE INTO XXX:SELECT 1316656;”
  • UUID: Disadvantages: Unordered, too long string, occupying space, affecting retrieval performance.
  • MongoDB solution: Use ObjectId. Disadvantages: Cannot increment.

• Principle of TDDL SEQUENCE in Distributed Mode

  • Create a sequence table in the database to record the maximum number of ids currently in use.
  • Each client host caches an ID range (for example, 1000 to 2000) and updates the maximum NUMBER of ids in the sequence table.
  • Different ID ranges are set between clients and hosts. The optimistic locking mechanism is used to control concurrency.

• Brief Introduction to my Understanding of DDD Driven Design

  • Concept: DDD addresses the fragmentation of the traditional software development process (analysis-design-coding) to avoid the failure of software delivery (and demander assumptions) due to unclear initial analysis or inconsistent information flow during software development. DDD emphasizes the domain-centric nature of everything, the role of Domain experts, the definition of the Domain model before development, and the Domain model can guide development (the so-called drive).
  • Process: understand the field, split the field, refine the field, the accuracy of the model depends on the depth of the model understanding.
  • Design: Modeling tools such as aggregations, entities, value objects, factories, warehouses, domain services, and domain events are presented in DDD to help with domain modeling.

• Summary of Basic Knowledge of Domain-Driven Design

  • Doamin is essentially a problem domain, such as an e-commerce system, a forum system, etc.
  • Bounded Context: Describing the relationships between subdomains, which can be simply understood as a subsystem or component module.
  • Domain Model: The core of DDD is to establish the correct Domain Model (using common description Language, tool – Domain common language); Reflect the nature of business requirements, both entities and processes; It runs through the whole process of software analysis, design and development. Common ways to express domain models: diagrams, code, or text;
  • Domain common Language: a language or tool that domain experts, developers and designers can use immediately.
  • Classical hierarchical architecture: user interface/presentation layer, application layer, domain layer, infrastructure layer, is a four-tier architecture mode.
  • Modes to use:
    • As few associations as possible, as far as possible single, as far as possible to reduce the overall complexity.
    • Entity: A unique identifier in a domain. The attributes of an Entity should be as few as possible.
    • Value Object: a simple Object with no unique identifier and immutable property values, such as Date.
    • Domain Service: coordinate multiple Domain objects, only methods have no state (no data); It can be divided into application layer service, domain layer service and basic layer service.
    • Aggregate and Aggregate Root: Aggregate defines a set of related objects that have a cohesive relationship; The aggregation root is the only element referenced to the aggregation; When modifying an aggregate, it must be at the transaction level; In most domain models, 70% of aggregations typically have only one entity and 30% have only 2-3 entities; If an aggregation has only one entity, that entity is the aggregation root; If there are multiple entities, then we can think about which objects within the aggregate have meaning and can interact directly with the outside world;
    • Factory: Similar to the Factory pattern in design pattern.
    • Repository: Persist to DB, manage objects, and only to aggregate design repositories.

• The Road to Domain-Driven Design (DDD) Implementation

  • Convergence: For example, a Car contains components such as an Engine, a Wheel, and a Tank.

• Domain Driven Design Series (2) Brief Analysis of the Concept, Difference and Use of VO, DTO, DO and PO

TODO

• DODAF2.0 methodology
• DODAF2.0: how to land the power perspective

TODO

• What is Service Mesh?

• “Architectural Design: How to Review Architectural Design”
• Everyone is An Architect: Non-functional Requirements

System or system! In addition, each company needs to develop its own check list based on its own needs and goals

• Why can’t you do a Code Review?

  • Code review does a good job, lies in the system construction.

• Code Review from Scratch

• Code Review Checklist

• The Java Code Review Checklist

• How to Do Code Review with GitLab

XP – eXtreme Programming

• Mainstream Agile Development Methods: Extreme Programming XP

  • Is a methodology to guide developers.

  • 4 values:

    • Communication: Encourage oral communication to improve efficiency.
    • Simple: enough is enough.
    • Feedback: timely feedback, inform the relevant people.
    • Courage: Embracing change and reinventing.

  • The five principles: quick feedback, simplicity assumption, gradual change, advocate change (quick steps), and good work (quick steps without quality).

  • Five jobs: Stage sprint; Sprint planning meeting; Daily stand-up sessions; Review after sprint; Retrospective meeting.

TODO

TODO

Article 253 of China’s Criminal Law stipulates:

• State organs or financial, telecommunications, transportation, education, medical and other units of staff, in violation of the provisions of the state, will this unit in the process of perform their duties, or providing services for citizens personal information, sell or illegally provide to others, if the circumstances are serious, shall be sentenced to fixed-term imprisonment of not more than three years or criminal detention, and concurrently or independently be sentenced to a fine.
• Whoever steals or illegally obtains the aforesaid information by other means, if the circumstances are serious, shall be punished in accordance with the provisions of the preceding paragraph.
• Where a unit commits any of the crimes mentioned in the preceding two paragraphs, it shall be fined, and the persons who are directly in charge and the other persons who are directly responsible for the crime shall be punished in accordance with the provisions of the preceding paragraphs.

The Supplementary provisions (iv) of the Supreme People’s Court and The Supreme People’s Procuratorate on the implementation of crimes determined in the Criminal Law of the People’s Republic of China stipulates that, in violation of the provisions of Paragraph 1 of Article 253 of the Criminal Law, it constitutes “the crime of selling or illegally providing citizens’ personal information”; Violate the provisions of article 253, paragraph 2 of the Criminal Law, constitute the “crime of illegally obtaining citizens’ personal information”

• Crime of Illegally obtaining Citizens’ Personal Information

• 36kr
• Techweb

Abroad:

• DZone
• Reddit

• Deep Understanding of Spring Cloud and Microservice Building

• Ali Technical Reference Atlas – Research and Development

• Ali Technical Reference Atlas – Algorithms

• 2018 Meituan Review Technology New Year Products (Collection) 70M

• InfoQ Architects monthly

• The Way of The Architect

• Alibaba Java Development Manual jd Taobao

• CTO Says jd Taobao
• Top of Technology Management
• Netease 1001 Nights: Internet Product Project Management Combat jingdong Taobao

TODO

Abroad:

• Quick Code
  • Free online technical tutorials.
• gitbook.com
  • There are some Chinese e-books.
• Cheatography
  • Cheat Sheets, a one-page document website.

Event Release Platform:

• Active line

• Ali cloud
• Tencent cloud
• Baidu cloud
• Sina cloud
• Kingsoft cloud group
• Amazon Cloud (AWS)
• Google cloud
• Microsoft’s cloud