解决问题： druid数据库连接池一直重连导致服务器内存爆满

druid数控库连接池默认是for(;😉 一直重连，会导致web程序一直打印error日志，生产服务器内存撑满.

1 对于集成druid有两种方式 我们分别讲如何处理

ps：网上的其他人都是复制粘贴，可能能解决你的问题，但是不全面.

1.1 引入了druid-spring-boot-starter

   <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>

 此种方式是最方便的，直接采用网上说的方式即可，原因  druid-spring-boot-starter已经帮你内置好了配置类.
 并且springboot设计语言是约定大于配置，所以直接修改配置即可 如下： yml 修改下即可

  ## 数据库连接池重连 当数据库断开后一直链接   durid 每500毫秒重连一次 也就是1秒2两次 我们这里设置5分钟连不上就不在链接了 5*60*1000/500=600  这里根据实际情况设置
spring.datasource.druid.break-after-acquire-failure=true
spring.datasource.druid.connection-error-retry-attempts=5

1.2 引入了 druid

这种方式我们一般会自己配置druid配置类

 <dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>druid</artifactId>
	</dependency>

代码如下：

package com.hwsafe.hcs.base.config;

import java.sql.SQLException;

import javax.sql.DataSource;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
@Slf4j
@Configuration
public class DruidConfiguration {
    @Value("${spring.datasource.url}")
    private String url;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;

    @Value("${spring.druid.initialSize}")
    private int initialSize;

    @Value("${spring.druid.minIdle}")
    private int minIdle;

    @Value("${spring.druid.maxActive}")
    private int maxActive;

    @Value("${spring.druid.maxWait}")
    private int maxWait;

    @Value("${spring.druid.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;

    @Value("${spring.druid.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;

    @Value("${spring.druid.validationQuery}")
    private String validationQuery;

    @Value("${spring.druid.testWhileIdle}")
    private boolean testWhileIdle;

    @Value("${spring.druid.testOnBorrow}")
    private boolean testOnBorrow;

    @Value("${spring.druid.testOnReturn}")
    private boolean testOnReturn;

    @Value("${spring.druid.poolPreparedStatements}")
    private boolean poolPreparedStatements;

    @Value("${spring.druid.maxPoolPreparedStatementPerConnectionSize}")
    private int maxPoolPreparedStatementPerConnectionSize;

    @Value("${spring.druid.filters}")
    private String filters;

    @Value("{spring.druid.connectionProperties}")
    private String connectionProperties;

    /**
     * 重连是否限制次数 默认否
     */
    @Value("${spring.datasource.druid.break-after-acquire-failure}")
    private boolean breakAfterAcquireFailure;

    /**
     * 限制重连时的次数 官方默认是1
     */
    @Value("${spring.datasource.druid.connection-error-retry-attempts:1}")
    private int connectionErrorRetryAttempts;

    /**
     * 重连的频率  官方默认500 毫秒一次
     */
    @Value("${spring.datasource.druid.time-between-connect-error-millis:500}")
    private int timeBetweenConnectErrorMillis;

    @Bean
    @Primary
    public DataSource dataSource() {
        DruidDataSource datasource = new DruidDataSource();

        datasource.setUrl(url);
        datasource.setUsername(username);
        // 这里可以做加密处理
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);

        // configuration
        datasource.setInitialSize(initialSize);
        datasource.setMinIdle(minIdle);
        datasource.setMaxActive(maxActive);
        datasource.setMaxWait(maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(
                timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setValidationQuery(validationQuery);
        datasource.setTestWhileIdle(testWhileIdle);
        datasource.setTestOnBorrow(testOnBorrow);
        datasource.setTestOnReturn(testOnReturn);
        datasource.setPoolPreparedStatements(poolPreparedStatements);
        datasource.setMaxPoolPreparedStatementPerConnectionSize(
                maxPoolPreparedStatementPerConnectionSize);
        datasource.setBreakAfterAcquireFailure(breakAfterAcquireFailure);
        // 增加控制druid数据库连接池对于 重连机制的修改  @add by Xiaowb @20220624  这里官方的程序是有问题的 暂时先不改 最新版本换成了定时任务 ，之前是Tread.sleep
        if(breakAfterAcquireFailure){
            datasource.setBreakAfterAcquireFailure(breakAfterAcquireFailure);
            datasource.setTimeBetweenConnectErrorMillis(timeBetweenConnectErrorMillis);
            datasource.setConnectionErrorRetryAttempts(connectionErrorRetryAttempts);
        }
        try {
            datasource.setFilters(filters);
        } catch (SQLException e) {
            log.error("datasource.setFilters error:{}",e);
        }
        datasource.setConnectionProperties(connectionProperties);

        return datasource;
    }

    @Bean
    public ServletRegistrationBean<StatViewServlet> statViewServlet() {
        ServletRegistrationBean<StatViewServlet> servletRegistrationBean = new ServletRegistrationBean<>(
                new StatViewServlet(), "/druid/*");
        // 设置ip白名单
        servletRegistrationBean.addInitParameter("allow", "127.0.0.1");
        // 设置ip黑名单，优先级高于白名单
        servletRegistrationBean.addInitParameter("deny", "192.168.21.139");
        // 设置控制台管理用户
        servletRegistrationBean.addInitParameter("loginUsername", "root");
        servletRegistrationBean.addInitParameter("loginPassword", "root");
        // 是否可以重置数据
        servletRegistrationBean.addInitParameter("resetEnable", "false");
        return servletRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean<WebStatFilter> statFilter() {
        // 创建过滤器
        FilterRegistrationBean<WebStatFilter> filterRegistrationBean = new FilterRegistrationBean<>(
                new WebStatFilter());
        // 设置过滤器过滤路径
        filterRegistrationBean.addUrlPatterns("/*");
        // 忽略过滤的形式
        filterRegistrationBean.addInitParameter("exclusions",
                "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        return filterRegistrationBean;
    }

}

我的配置如下图

 ##数据库连接池重连 当数据库断开后一直链接   durid 每500毫秒重连一次 也就是1秒2两次 我们这里设置5分钟连不上就不在链接了 5*60*1000/1000=300  这里根据实际情况设置
spring.datasource.druid.break-after-acquire-failure=true
spring.datasource.druid.connection-error-retry-attempts=10
spring.datasource.druid.time-between-connect-error-millis=1000

我们看下效果图 大致是每一秒重连一次 重连10次 这里由于我的是最新版本的druid有点问题，1.x是没有问题的