• Introduction to Linux basic commands 13: startup process


    firmware(Firmware) refers to the program code at the bottom of the device that allows the device to run. The simple understanding is: software fixed on hardware. Many devices in the computer have firmware (such as hard disk, mouse, optical drive, U disk, etc.), and the first thing to read is the firmware on the motherboard […]

  • Change the log level dynamically when Flink is running


    background Flink on Yan cluster mode, which is used when submitting tasksFLINK_CONFG_DIRLowerlog4j.properties, the output level of the log cannot be changed dynamically; The official does not support specifying log configuration files by reference. Please check the detailsYarnConfigOptionsInternalDescription on class If you want to specify the log output level for different tasks, you can only use […]

  • Raftmlp do MLP based models dream of winning over CV?


    RaftMLP: Do MLP-based Models Dream of Winning Over Computer Vision? Original document:https://www.yuque.com/lart/pa… Understanding papers from abstracts For the past ten years, CNN has reigned supreme in the world of computer vision, but recently, Transformer is on the rise. However, the quadratic computational cost of self-attention has become a severe problem of practice. It is pointed […]

  • Minutes of December meeting of openmldb


    OpenMLDBThe community recently invited community contributors and users to hold a community meeting in December. The main contents of this meeting are as follows: Introduction to the current development progress of version 0.4.0 Discuss some features in version 0.5.0 planning and collect community feedback Community activity forecast in January Community feedback: About monitoring latency and […]

  • In depth analysis of volatile (Java)


    Bytecode levelThrough javac singleton Java compiles the class into a class file, and then through javap – V – P singleton Class Command decompile to view bytecode files- P is used to display all classes and membersD:\JavaSE\JavaProject\design-pattern\src\main\java>javap -p -v Singleton.classClassfile /D:/JavaSE/JavaProject/design-pattern/src/main/java/Singleton.class Last modified 2021-4-19; size 509 bytes MD5 checksum fc6fcd094d2d9cdf0edd20d59c6b0d22 Compiled from “Singleton.java”public class Singleton […]

  • Mvcc mechanism in MySQL


    Mvcc (multi version concurrency control), multi version concurrency control. Mvcc is a method of concurrency control. By maintaining the records of multiple versions of data, it solves the concurrent read-write conflict in a lock free way. The purpose is to avoid locking in case of read-write conflict. MySQL’s InnoDB engine uses mvcc. Related concepts To […]

  • Microservice architecture | 4.2 service interface call based on feign and openfeign


    catalogue preface 1. Basic knowledge of openfeign 1.1 what is feign 1.2 what problems does feign solve 1.3 difference and comparison between feign and openfeign 2. Enable feign support on the service consumer side 2.1 introduction of POM XML dependency 2.2 add comments on the main program class 2.3 add notes on the business interface […]

  • Basic knowledge of affairs


    What is a transaction? Transactions are in the databaseminimumOf processing unitTask set。 It can be one SQL statement or a collection of multiple SQL operations. It can ensure that these task sets are either complete or completeIt’s all done, orNo execution, will not be in an intermediate state. Database is orientedMultithreading and multi-userDesigned to be […]

  • Issue 36: MySQL native level split table


    introduction In the previous chapter, we discussed vertical data splitting. Today, we will continue to discuss data splitting: horizontal splitting! There are some differences between horizontal splitting and vertical splitting. The smallest unit of vertical splitting is a field, which has a strong correlation with the business. The specific business corresponds to the specific split […]

  • Efcore implementation value object of DDD


    Efcore implementation value object of DDD Region public record Region { public long Id { get; init; } public MultilingualString Name { get; init; } public Area Area { get; init; } public RegionLevel Level { get; private set; } public long? Population { get; private set; } // population public Geo Location { get; […]

  • Big data development – persistence and caching of spark RDD


    1. RDD caching mechanism, cache, persist One reason spark is very fast is that RDD supports caching. After successful caching, if the data set is used in subsequent operations, it will be obtained directly from the cache. Although there is a risk of cache loss, due to the dependency between RDDS, if the cache data […]

  • Isolation level and concurrency of MySQL transactions


    Isolation level and concurrency of MySQL transactions MySQL version: 8.0.27 1、 Problems faced by concurrent transaction execution CREATE TABLE `user` ( `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT, `Name ` varchar (10) not null comment ‘, `Age ` tinyint (3) unsigned not null comment ‘age’, PRIMARY KEY (`id`) USING BTREE ) ENGINE=InnoDB CHARACTER SET=utf8mb4; Insert into […]