Druid+mysql+mybatis做定时批量操作出现CommunicationsException: Communications link failure

Posted 2022-08-11 baby123

最近使用Druid+mysql+mybatis实现定时批量操作，过一段时间就会抛出

2019-08-21 11:43:51.731 [task-3] ERROR com.alibaba.druid.pool.DruidPooledStatement - CommunicationsException, druid version 1.1.17, jdbcUrl : jdbc:mysql://localhost:3306/bim?serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&autoReconnect=true&failOverReadOnly=false, testWhileIdle true, idle millis 8007, minIdle 5, poolingCount 4, timeBetweenEvictionRunsMillis 60000, lastValidIdleMillis 8007, driver com.mysql.cj.jdbc.Driver, exceptionSorter com.alibaba.druid.pool.vendor.MySqlExceptionSorter
2019-08-21 11:43:51.732 [task-3] ERROR com.alibaba.druid.pool.DruidDataSource - discard connection
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet successfully received from the server was 8,003 milliseconds ago. The last packet sent successfully to the server was 8,003 milliseconds ago.

查了很多资料有人说要修改 mysql连接的超时时间，但是我这也没跑超过8小时

导致这种问题的原因：

　　应用线程池还hold着数据库已经断掉的连接——“脏连接”

配置了validationQuery——select 1，但是查了下mysql的执行的全部log，根本执行该语句

调试下发现 usePingMethod为true 

源码中usePingMethod为true ，就不会执行validateQuery部分 

public boolean isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) throws Exception 
        if (conn.isClosed()) 
            return false;
        
        if (this.usePingMethod) 
            if (conn instanceof DruidPooledConnection) 
                conn = ((DruidPooledConnection) conn).getConnection();
            
            if (conn instanceof ConnectionProxy) 
                conn = ((ConnectionProxy) conn).getRawObject();
            
            if (this.clazz.isAssignableFrom(conn.getClass())) 
                if (validationQueryTimeout < 0) 
                    validationQueryTimeout = 1;
                
                try 
                    this.ping.invoke(conn, new Object[]Boolean.valueOf(true), Integer.valueOf(validationQueryTimeout * 1000));
                 catch (InvocationTargetException e) 
                    Throwable cause = e.getCause();
                    if (cause instanceof SQLException) 
                        throw (SQLException) cause;
                    
                    throw e;
                
                return true;
            
        

        String query = validateQuery;
        if (validateQuery == null || validateQuery.isEmpty()) 
            query = "SELECT 1";
        
        stmt = null;
        rs = null;
        try 
            stmt = conn.createStatement();
            if (validationQueryTimeout > 0) 
                stmt.setQueryTimeout(validationQueryTimeout);
            
            rs = stmt.executeQuery(query);
            return true;
         finally 
            JdbcUtils.close(rs);
            JdbcUtils.close(stmt);
        
   

解决的方法：

　　使用应用级别的心跳检测，不使用系统级别的 ping（禁止mysql connector自带的ping机制）

　　在jvm参数配置 -Ddruid.mysql.usePingMethod=false

附：

application.properties中的配置

## 数据库访问配置, 使用druid数据源
spring.datasource.druid.db-type=mysql
spring.datasource.druid.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.druid.url = jdbc:mysql://localhost:3306/bim?serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&autoReconnect=true&failOverReadOnly=false
spring.datasource.druid.username=bimengine
spring.datasource.druid.password=fgBQLZpgDaxH7xuu
# 连接池配置
spring.datasource.druid.initial-size=5
spring.datasource.druid.min-idle=5
spring.datasource.druid.max-active=20
# 配置获取连接等待超时的时间
spring.datasource.druid.max-wait=30000
spring.datasource.druid.test-while-idle=true
spring.datasource.druid.test-on-borrow=false
spring.datasource.druid.test-on-return=false
spring.datasource.druid.validation-query= select 1
spring.datasource.druid.validation-query-timeout=60000
spring.datasource.druid.min-evictable-idle-time-millis=300000
spring.datasource.druid.time-between-eviction-runs-millis=60000

# 打开PSCache，并且指定每个连接上PSCache的大小
spring.datasource.druid.pool-prepared-statements=true
spring.datasource.druid.max-open-prepared-statements=20
spring.datasource.druid.max-pool-prepared-statement-per-connection-size=20

# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，‘wall‘用于防火墙
spring.datasource.druid.filters=stat,wall
# WebStatFilter配置
spring.datasource.druid.web-stat-filter.enabled=true
spring.datasource.druid.web-stat-filter.url-pattern=/*
spring.datasource.druid.web-stat-filter.exclusions=‘*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*‘
#是否启用StatFilter默认值true
spring.datasource.druid.stat-view-servlet.enabled=true
# 访问路径为/druid时，跳转到StatViewServlet
spring.datasource.druid.stat-view-servlet.url-pattern=/druid/*
#druid监控管理界面登录帐号
spring.datasource.druid.stat-view-servlet.login-username=admin
#druid监控管理界面登录密码
spring.datasource.druid.stat-view-servlet.login-password=admin@tydt
spring.datasource.druid.stat-view-servlet.allow=127.0.0.1

# 配置StatFilter
spring.datasource.druid.filter.stat.log-slow-sql=true