Programmer Group

Waiting for table metadata lock The CPU and IOPS on line are not very low, but there is no response to DDL(drop|truncate|rename|repair) on a table. In the process list, you will see the newspaper Waiting for table metadata lock. Interpretation of WFTML in MySQL Manual (excerpt) MySQL uses metadata locking to manage concurrent access t ...

We know that running SQL statements in PL/SQL programs is expensive because the SQL statements are submitted to the SQL engine for processing. This control transfer between the PL/SQL engine and the SQL engine is called context-switching, and each time it is switched, there is additional overhead. See the following picture:         Ho ...

Catalog Preface Construction project and other preparatory work Create a database Create Koa2 Project Other Requirements Packages for Installation Project Remove redundant files and re-plan project catalogs configuration file Plan sample routing and create new related files Implementing Data Access and Business Logic Related ...

Spring Boot QuickStart (3) - Web & Restful Environment: Spring Boot 1.5.4 Spring Boot allows you to quickly create a Web & Restful application. At least before you start using Spring Boot, you need to understand the following usages: Define routing, define HTTP methods Get parameters such as Header, GET, POST, path, etc. Cookie, Sessio ...

Flow chart   First, we need to define a global OPENID which is similar to the current login user ID of the ordinary account password login system, because I am the MVC framework. Here, I define a controller base class BaseController and then define OPENID in BaseController. 1 public class BaseController : Controller 2 { 3 publ ...

Inspiration - because recently we have been working on RNN-based NLP, where no matter what cell, lstm, GRU or cnn are embedding representations based on words; embdding of words is to represent each word as a vector, and then train the values of these vectors through bp, which is a wonderful idea, so I try to apply this idea to logistic regress ...

Written in frontThe previous article explained the type of session for you. Today, this article will lead you to implement a simple session server step by step, mainly to let you understand the working process of session server. Of course, for small and medium-sized websites, this structure is also fully adequate. The main structure of this sec ...

FileManager Chinese name is File Manager, also known as File Browser, which provides us with a visual interface to manage files and folders. With FileManager, we can browse, add, print, modify (file attributes), rename, search and so on a lot of very useful operations. CKeditor believes that friends are very familiar with it. It's a rich text e ...

In ASP.NET MVC, view data can be accessed through ViewBag, ViewData and TempData, where ViewBag is Dynamic and ViewData is Dictionary. They are defined as follows: 1 public dynamic ViewBag { get; } 2 public ViewDataDictionary ViewData { get; set; } Controller code: 1 public ActionResult Index() 2 { 3 ViewBag.Message_ViewBag = "I am viewb ...

I. Preliminary Analysis of Cluster Technology 1. tomcat cluster multi-application servers, sharing pressure and ensuring high availability of services, using tomcat cluster to achieve cluster environment, Manager is responsible for managing session sharing. 2. The web server adopts Apache, which is responsible for load balancing between appl ...