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悲观锁:总是假设最坏的情况,每次去拿数据的时候都认为别人会修改,所以每次在拿数据的时候都会上锁,这样别人想拿这个数据就会阻塞直到它解锁。传统的关系型数据库里边就用到了很多这种锁机制,比如行锁,表锁等,读锁,写锁等,都是在做操作之前先上锁。就像for update,再比如Java里面的同步原语sync 阅读全文
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<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <!--排除 tomcat--> <exclusion> <g 阅读全文
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远程代码采用免费服务器 搭建测试环境 并示例采用 centos 7.6 搭建宝塔方便安装扩展Xdebug 安装 Xdebug 扩展 Xdebug验证方法 # 本机配置项 [xdebug] zend_extension="/Applications/MAMP/bin/php/php5.6.40/lib 阅读全文
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查找所有png图片 find . -name "*.png" 计算图片md5值 md5sum ./upload/2022-03-02/25220_133732_1187.png e489e09d7b538a9ef7b2bfa29ccd0cbd ./upload/2022-03-02/25220_13 阅读全文
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export LC_ALL=en_US.UTF-8 export LANG=en_US.UTF-8 # If you come from bash you might have to change your $PATH. # export PATH=$HOME/bin:/usr/local/bin: 阅读全文
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<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.6.0</version> </dependency> package top.xiongmingca 阅读全文
![zookeeper CURD增删改查【二】](https://img2020.cnblogs.com/blog/2079396/202108/2079396-20210831175007696-1636625610.png)
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安装 brew install zookeeper mac zookeeper 命令如下 zkServer {start|start-foreground|stop|version|restart|status|print-cmd} p配置文件目录 cat /usr/local/etc/zookee 阅读全文
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一、下载 官方连接 https://archive.apache.org/dist/zookeeper/ yum install wget -y wget https://archive.apache.org/dist/zookeeper/zookeeper-3.6.0/apache-zookeep 阅读全文
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1)引入依赖 <!-- https://mvnrepository.com/artifact/quartz/quartz --> <dependency> <groupId>quartz</groupId> <artifactId>quartz</artifactId> <version>1.5.2 阅读全文
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删除原有mariadb [root@test mysql]# rpm -qa | grep mariadb mariadb-devel-5.5.52-1.axs7.x86_64 mariadb-libs-5.5.52-1.axs7.x86_64 [root@test mysql]# rpm -e - 阅读全文