• understand Object.defineProperty


    understand Object.defineProperty This article was written on October 13, 2020 Object.defineProperty Used to define a new property on an object or modify an existing property and return the object. What do you mean? Don’t panic to understand, let’s take an example to see. const obj1 = {}; Object.defineProperty(obj1, ‘property1’, { value: 42, writable: false, }); […]

  • Operating system-i / O model


    1. What is I / O? In UNIX, everything is a file and a binary stream. In the process of information exchange, we operate on these flows, which is what we usually callI / O (input output) operationThe computer records one for each streamFile descriptor — FD (file descriptor)To distinguish the operation of each file! […]

  • Super detailed! Nginx log configuration practice


    preface Nginx logs are useful for statistics and system service troubleshooting. There are two main types of nginx logs:access_ Log and error_ Log (error log). By accessing the log, we can get the user’s IP address, browser information, request processing time and other information. Error logs record information about access errors, which can help us […]

  • Detailed explanation of Android JNI, let you thoroughly understand JNI (2): usage analysis


    catalog Usage analysis├ – 1. JNI function │ ├── 1.1、extern “C” │ ├── 1.2、JNIEXPORT、JNICALL3. Function name │ ├── 1.4、JNIEnv │ ├── 1.5、jobject𗍊 – 2. Mapping relations of Java, JNI and C / C + + basic types├ – 3. JNI descriptor (signature)Function static registration and dynamic registration1. Principle of dynamic registration2. Principle of static registration3. […]

  • Take you to the USB world


    1. What is USB The full name of USB is universal serial bus, universal serial bus. Its appearance is mainly to simplify the connection between personal computer and peripheral equipment and increase the usability. USB supports hot plug, and it is plug and play. In addition, it also has strong scalability and fast transmission speed. […]

  • Redis02 redis high performance and epoll


    Why is redis so fast Redis is basically a memory operation, so it is very fast Memory: 1. Addressing time: ns level 2. Bandwidth: very large Disk: 1. Addressing time: ms at ms level 2. Bandwidth: g / M Disk addressing is more than 10W times slower than memory addressing, so the stand-alone redis can […]

  • Understanding web server from Python Perspective


    summary:The web server is actually a network server running on a physical machine. It waits for the client to send a request to it, and then it responds to the client’s requested resources after receiving it successfully. The communication between client and server is realized by HTTP protocol. The client can be a browser or […]

  • Design of Linux high performance server


    C10K and c10m Many technologies in the field of computer are driven by demand. In the 1990s, due to the rapid development of the Internet, network servers can not support the rapid growth of user scale. In 1999, Dan Kegel put forward the famous C10 problem: 10000 client network connections are processed simultaneously on one […]

  • How to use PHP — wkhtmltopdf


    1、 Problem description Need to use PHP to generate PDF HTML, found a PHP extension, HTML2PDF, can only generate some simple HTML code, complex HTML + CSS can not generate. A powerful wkhtmltopdf was found online. 2、 Introduction to wkhtmltopdf The full name of the tool is “wkhtmltopdf”; it is a command-line tool that uses […]

  • Example of using flick datastream broadcaststream broadcast stream Scala


    1. Explanation on the official websiteBroadcast statusIntroduced to support use cases where some data from one stream needs to be broadcast to all downstream tasks, where it is stored locally and used to process all incoming elements on another stream. As an example of the natural fit of broadcast state, we can imagine a low […]

  • Interviewer: please introduce let const Object.freeze (), set and get


    Top of the front everyday: In this series, every little partner can participate in the problem solving, and show your answers in the comment area. JavaScript is a quite dynamic language, and everyone has their own style and opinions. Welcome to actively provide daily questions and different answers below Every day, I invite some people […]

  • Nginx optimization (I) CPU correlation


    Nginx optimization Increase the effective time of using CPU by nginx Enable it to use all CPU resources Do not scramble for CPU resources between nginx processes (busy worker processes should not yield, resource scheduling should not yield resources) Do not compete with other processes for resources (non nginx processes that increase priority to take […]