why checking connection so frequently with druid?

[e7]

datasource:
      names: master,slave0
      master:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://192.168.1.229:3306/xxxx?useSSL=false&useUnicode=true&serverTimezone=UTC&characterEncoding=UTF-8&autoReconnect=true
        username: xxxx
        password: 123456
        druid:
          test-on-borrow: false
          test-while-idle: true
          validation-query: SELECT 1
          time-between-eviction-runs-millis: 30000
          min-evictable-idle-time-millis: 30000
          connection-init-sqls: set names utf8mb4;
      slave0:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://192.168.1.229:3306/xxxx?useSSL=false&useUnicode=true&serverTimezone=UTC&characterEncoding=UTF-8&autoReconnect=true
        username: xxxx
        password: 123456
        druid:
          test-on-borrow: false
          test-while-idle: true
          validation-query: SELECT 1
          time-between-eviction-runs-millis: 30000
          min-evictable-idle-time-millis: 30000
          connection-init-sqls: set names utf8mb4;

2019-05-08 09:19:34.444  INFO 10660 --- [nio-8080-exec-7] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:34.444  INFO 10660 --- [nio-8080-exec-7] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:35.441  INFO 10660 --- [io-8080-exec-10] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:35.441  INFO 10660 --- [io-8080-exec-10] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:36.448  INFO 10660 --- [nio-8080-exec-9] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:36.448  INFO 10660 --- [nio-8080-exec-9] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:37.449  INFO 10660 --- [nio-8080-exec-5] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:37.449  INFO 10660 --- [nio-8080-exec-5] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:38.455  INFO 10660 --- [nio-8080-exec-6] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:38.456  INFO 10660 --- [nio-8080-exec-6] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:39.458  INFO 10660 --- [nio-8080-exec-2] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:39.458  INFO 10660 --- [nio-8080-exec-2] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0
2019-05-08 09:19:40.455  INFO 10660 --- [nio-8080-exec-1] ShardingSphere-SQL                       : Rule Type: master-slave
2019-05-08 09:19:40.456  INFO 10660 --- [nio-8080-exec-1] ShardingSphere-SQL                       : SQL: /* ping */ SELECT 1 ::: DataSources: slave0

[e7]

<properties>
  <java.version>1.8</java.version>
  <sharding-sphere.version>3.1.0</sharding-sphere.version>
</properties>

[KomachiSion]

Hi @e7, it looks like you use sharding-jdbc-spring-boot-starter 3.1.0, you can remove druid prefix and retry. such as

datasource:
      names: master,slave0
      master:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://192.168.1.229:3306/xxxx?useSSL=false&useUnicode=true&serverTimezone=UTC&characterEncoding=UTF-8&autoReconnect=true
        username: xxxx
        password: 123456
        test-on-borrow: false
        test-while-idle: true
        validation-query: SELECT 1
        time-between-eviction-runs-millis: 30000
        min-evictable-idle-time-millis: 30000
        connection-init-sqls: set names utf8mb4;
      slave0:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://192.168.1.229:3306/xxxx?useSSL=false&useUnicode=true&serverTimezone=UTC&characterEncoding=UTF-8&autoReconnect=true
        username: xxxx
        password: 123456
        test-on-borrow: false
        test-while-idle: true
        validation-query: SELECT 1
        time-between-eviction-runs-millis: 30000
        min-evictable-idle-time-millis: 30000
        connection-init-sqls: set names utf8mb4;

[e7]

@KomachiSion Thanks for replying, I have tried it, still not working

[KomachiSion]

@KomachiSion Thanks for replying, I have tried it, still not working

Can you provide your full configuration or your example code to GitHub?
I check your log info and find that it seems execute SELECT 1 by ShardingDatasource not by DruidDatasource

[e7]

Here is an example which can reproduce my problem.
example-sharding-jdbc-ping

windows 7 64bit
java8
idea 2018.3

[KomachiSion]

OK, I find the reason for this problem. The problem caused by spring-boot-actuator, which will check datasource connection healthy before each invoke.
You can see some detail info in method org.springframework.boot.actuate.jdbc.DataSourceHealthIndicator.doDataSourceHealthCheck.

If you wanna to debug for this problem, you can set breakPoint in method io.shardingsphere.shardingjdbc.jdbc.core.statement.MasterSlaveStatement.executeQuery(String sql) and check the JVM stacks.

So for ShardingSphere, it just execute a normal SQL called by spring health check. Not problems.

[e7]

@KomachiSion Yes, it's NOT a problem, thanks for your time and patience, and it can be disabled by the following configuration

management:
  health:
    db:
      enabled: false