azkaban multi node deployment and installation record

Environmental preparation jdk8+ mysql Node Division centosx1 centosx2 centosx3 web-server exe-server exe-server mysql Here, the hosts file is edited and selinux and firewalld are closed [root@centos7x3 azkaban-exec-server]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain ...

Posted on Sat, 27 Jun 2020 04:26:17 -0400 by siminder

The solution of lock in Java

1. Optimistic lock and pessimistic lock Optimistic locks and pessimistic locks should be the first two types of locks that every developer contacts. Application scenarios are mainly used to update data, which is also one of the most important scenarios for using locks. The main process of updating d ...

Posted on Sat, 27 Jun 2020 04:21:02 -0400 by phpbaby2009

MySQL 8.0 window function practice and summary

Before MySQL 8.0, it was quite painful to do data ranking statistics, because there was no window function like Oracle, SQL SERVER, PostgreSQL and other databases. However, with the addition of window functions in MySQL 8.0, it is no longer a problem for this kind of statistics. This paper introduces MySQL window functions with common sorting e ...

Posted on Sat, 27 Jun 2020 03:42:25 -0400 by always_confused

Beauty of Mybatis source code: 2.13. Parse the databaseIdProvider element and configure the database type unique flag generator

Parse the databaseIdProvider element and configure the database type unique flag generator An interface named DatabaseIdProvider is defined in mybatis. The function of this interface is to obtain the unique flag of different data sources in mybatis. DatabaseIdProvider defines two methods, setProperties() method is used to configure custom prope ...

Posted on Sat, 27 Jun 2020 02:10:05 -0400 by PHPoracle

JFinal unpacking evaluation, I'm serious this time

introduction I met JFinal unexpectedly when I was looking at the server container yesterday. Before, my impression of JFinal was just that it was a framework developed by Chinese people to integrate Spring family buckets. Later I checked it, as if things were not so simple. JFinal has won the best open source project of OSChina for many y ...

Posted on Fri, 26 Jun 2020 22:44:16 -0400 by ludwig

mongoDB and pymongo learning

Contents of this article The foregoing install linux Installation docker container deployment Windows setup use GUI viewer Differences between mongoDB and relational database mongoDB basic syntax pymongo module usage The foregoing mongoDB should be a non relational database according to the ...

Posted on Fri, 26 Jun 2020 04:24:11 -0400 by vertmonkee

Tabs of EasyUi

Tabs control What is Tabs Tabs use cases Properties of Tabs Events for Tabs Tabs method Tabs panel Create a tab Right click to close tabs What is Tabs Tabs are one of the most popular navigation modes (like menu bar and vertical navigation). The biggest advantage of tabs is that users are familiar w ...

Posted on Fri, 26 Jun 2020 04:22:00 -0400 by nikkio3000

Timeout: Pool empty. Unable to fetch a connection in 30 seconds, none available

org.apache.tomcat.jdbc.pool.ConnectionPool View source code private PooledConnection borrowConnection(int wait, String username, String password) throws SQLException { if (isClosed()) { throw new SQLException("Connection pool closed."); } //end if //get the curr ...

Posted on Fri, 26 Jun 2020 03:29:04 -0400 by callmecheez

Multithreading - thread pool

Application of pooling Technology: thread pool, database connection pool, http connection pool, etc. The idea of pooling technology is mainly to reduce the consumption of resources obtained each time and improve the utilization rate of resources. Benefits of using thread pools: Reduce resource co ...

Posted on Fri, 26 Jun 2020 01:59:12 -0400 by Loriq

Beego Learning Notes 14:Session Control

Session Control 1> Session s are often used as global variables, such as logging the currently logged-in user or passing data between pages. 2> The session module is built in the Beego framework. Currently, the session module supports back-end engines including memory, cookie s, file s, mysql, redis, couchbase, memcache, postgres. Users c ...

Posted on Thu, 25 Jun 2020 12:20:31 -0400 by JetJagger