Programmer Think

Official Documents https://hadoop.apache.org/docs/r3.1.1/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html#Configuration_details ** 1. Resource Role Planning ** ** 2. Configuration ** 2.1 Backup of fully distributed cluster. If you ...

Preamble Introduction When we implement the RPC framework, we need to choose how sockets communicate.And we know that socket communication is similar to qq chatting in general, sending messages in the past and replying whenever possible.But our RPC ...

Data Acquisition Section Information Records of Users Browsing Items User Id Commodity Id Commodity types Add time userId itemId itemType time Information Record of User Collections User Id Id of Collection Goods Collection time userId collerctId c ...

order This article mainly studies dubbo's All Dispatcher. Dispatcher dubbo-2.7.3/dubbo-remoting/dubbo-remoting-api/src/main/java/org/apache/dubbo/remoting/Dispatcher.java @SPI(AllDispatcher.NAME) public interface Dispatcher { /** * dispatch the message to threadpool. * * @param handler * @param url * @return channe ...

Mode 1 (not recommended) Single parameter mode @Mapper public interface UserDao extends BaseMapper<User> { User selectList1(String username, String phone); } <select id="selectList1" resultMap="BaseResultMap"> select * from user where username= #{arg0} and phone=#{arg1} </select> Note: select * from user where us ...

Summary After the front and back ends are separated, because HTTP itself is stateless, Session is useless. After the project adopts the scheme of jwt, the main process of request is as follows: after the user logs in successfully, the server will create a JWT token (the current operation account is recorded in the token of jwt), and return the ...

Overview of Tomcat Session Firstly, HTTP is a stateless protocol, which means that every HTTP request initiated is a completely new request (without any connection with the previous request, the server will not retain any information of the previous request), and Session appears to solve this problem, associating every request on the client si ...

The last section describes how to submit consumer displacement. It is with the persistence of consumer displacement that consumers can continue to consume according to the previously stored consumption displacement when they are closing, rushing or e ...

Preface Learn how to upload and download files in the Struts 2 framework. File upload Struts 2 provides support for commons-fileupload components. Uploading files requires importing two Jar packages or (Maven dependencies) common-fileuplaod-x.x. ...

Recently, in the day after management, we need to upload some app package files. These packages are within several hundred megabytes in size. Normally, they are uploaded. They are not only very stressful to the server, but also consume server resourc ...