• The three popular databases of NoSQL are memcached, redis and mongodb


    NoSQL generally refers to non relational databases. With the continuous development of the Internet, the traditional relational database has been unable to cope with the websites of the new Internet model, especially the super large-scale and highly concurrent SNS type pure dynamic websites, which has exposed many insurmountable problems, while the non relational database has […]

  • Import mechanism of Python entry Foundation


    1、 Foreword This article is based on open source projects: github.com/pwwang/pyth… Supplement and expand the explanation, hoping to make readers understand one articlePythonofimport mechanism。 1.1 what is the import mechanism? Generally speaking, to execute a piece of Python code that references the code in another module, you need to use Python’s import mechanism. The import […]

  • Phase III day14 redis fragmentation mechanism redis sentinel mechanism


    Redis fragmentation mechanism ============= 1.1 why do you need a fragmentation mechanism If you need to store a large amount of memory data, if only one redis is used, the efficiency of redis cannot be guaranteed. A lot of time is wasted in addressing. Therefore, a mechanism is needed to meet this requirementThe fragmentation mechanism […]

  • Prometheus file based service discovery


    1、 File based service discovery The IP: port of the node server we want to monitor is written dead in thestatic_configsIt is not easy to maintain. So is there an automatic discovery mechanism?PrometheusMany automatic discovery mechanisms are provided. Here is a brief record of the file based service discovery mechanism. 1. Writing method of prometheus.yml […]

  • Record optimism and pessimism


    1. Basic concepts In the concurrent scenario, there will be data competition, which will eventually lead to data inconsistency. Optimistic lock and pessimistic lock are two different ideas to solve this kind of problem. Optimistic lock:Take an optimistic attitude when operating the data, thinking that other threads (coroutines) will not modify this part of the […]

  • Possible questions


    Possible questions Why use the spring framework / the role and benefits of the spring framework: The spring framework provides a container that can manage the components of an application. It also provides IOC and AOP mechanisms to decouple components, improve the flexibility of program structure, and enhance the maintainability and scalability of the system. […]

  • Analysis of java reference mechanism in Java programming development


    For a Java object, there are two main types of storage: one is the memory heap, which is unordered and is mainly used to store the created Java object; One is the memory stack, which is mainly used to store Java references, and then use Java references to point to Java objects in the management […]

  • Httpclientfactory combines Polly to easily implement the retry mechanism


    Httpclientfactory combines Polly to easily implement the retry mechanism Intro There is an API in our service that calls the third-party interface and sets the timeout. Recently, timeout occasionally occurs. Microsoft is providing itHttpClientFactoryAt the same time, it also provides aPollyWe can easily implement retry, fuse and other behaviors with the help of an extension […]

  • Principle analysis of Java method parameter transfer mechanism


    This article mainly introduces the principle analysis of Java method parameter transfer mechanism. It is introduced in great detail through example code, which has certain reference value for everyone’s study or work. Friends in need can refer to it If formal parameters are declared in a Java method, you must specify parameter values for these […]

  • Springcloud01: learning foreword


    1. Content overview Learning premise: JavaSE database front end Servlet Http Spring+SpringMVC+Mybatis SpringBoot Dubbo + zookeeper + distributed infrastructure Maven+Git Ajax+Json … How to learn at this stage There are four problems with microservices:1. There are many services. How can the client access them? ​ 2. With so many services, how do services communicate? ​ […]

  • Exploring rocketmq source code — Series1: transaction messages from the perspective of producer


    Introduction:Exploring rocketmq source code — Series1: transaction messages from the perspective of producer 1. Preface Apache rocketmq, as a well-known open source messaging middleware, was born in Alibaba and donated to Apache in 2016. From rocketmq 4.0 to the latest v4.7.1, it has won wide attention and praise both inside and outside Alibaba communities.Out of […]

  • How to understand the 101 exchange protocol used by mqtt?


    Students who have used mqtt know that when mqtt is connected, the status in the network panel is 101. Name Status Time mqtt 101(Switching Protocols) Pending So what exactly does 101 (switching protocols) mean?This article will take you to understand what 101 exchange protocol is and the protocol upgrade mechanism used by 101 exchange protocol. […]