Spring Boot JPA - configuring auto reconnect

问题:

I have a nice little Spring Boot JPA web application. It is deployed on Amazon Beanstalk and uses an Amazon RDS for persisting data. It is however not used that often and therefore fails after a while with this kind of exception:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 79,870,633 milliseconds ago.
The last packet sent successfully to the server was 79,870,634 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.

I am not sure how to configure this setting and can not find information on it on http://spring.io (a very good site though). What are some ideas or pointers to information?

回答1:

I assume that boot is configuring the DataSource for you. In this case, and since you are using MySQL, you can add the following to your application.properties up to 1.3

spring.datasource.testOnBorrow=true
spring.datasource.validationQuery=SELECT 1

As djxak noted in the comment, 1.4+ defines specific namespaces for the four connections pools Spring Boot supports: tomcat, hikari, dbcp, dbcp2 (dbcp is deprecated as of 1.5). You need to check which connection pool you are using and check if that feature is supported. The example above was for tomcat so you'd have to write it as follows in 1.4+:

spring.datasource.tomcat.testOnBorrow=true 
spring.datasource.tomcat.validationQuery=SELECT 1

Note that the use of autoReconnect is not recommended:

The use of this feature is not recommended, because it has side effects related to session state and data consistency when applications don't handle SQLExceptions properly, and is only designed to be used when you are unable to configure your application to handle SQLExceptions resulting from dead and stale connections properly.

回答2:

The above suggestions did not work for me. What really worked was the inclusion of the following lines in the application.properties

spring.datasource.testWhileIdle = true
spring.datasource.timeBetweenEvictionRunsMillis = 3600000
spring.datasource.validationQuery = SELECT 1

You can find the explanation out here

回答3:

I just moved to Spring Boot 1.4 and found these properties were renamed:

spring.datasource.dbcp.test-while-idle=true
spring.datasource.dbcp.time-between-eviction-runs-millis=3600000
spring.datasource.dbcp.validation-query=SELECT 1

回答4:

Setting spring.datasource.tomcat.testOnBorrow=true in application.properties didn't work.

Programmatically setting like below worked without any issues.

import org.apache.tomcat.jdbc.pool.DataSource;
import org.apache.tomcat.jdbc.pool.PoolProperties;    

@Bean
public DataSource dataSource() {
    PoolProperties poolProperties = new PoolProperties();
    poolProperties.setUrl(this.properties.getDatabase().getUrl());         
    poolProperties.setUsername(this.properties.getDatabase().getUsername());            
    poolProperties.setPassword(this.properties.getDatabase().getPassword());

    //here it is
    poolProperties.setTestOnBorrow(true);
    poolProperties.setValidationQuery("SELECT 1");

    return new DataSource(poolProperties);
}

回答5:

I have similar problem. Spring 4 and Tomcat 8. I solve the problem with Spring configuration

<bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource" destroy-method="close">
    <property name="initialSize" value="10" />
    <property name="maxActive" value="25" />
    <property name="maxIdle" value="20" />
    <property name="minIdle" value="10" />
     ...
    <property name="testOnBorrow" value="true" />
    <property name="validationQuery" value="SELECT 1" />
 </bean>

I have tested. It works well! This two line does everything in order to reconnect to database:

<property name="testOnBorrow" value="true" />
<property name="validationQuery" value="SELECT 1" />

回答6:

In case anyone is using custom DataSource

@Bean(name = "managementDataSource")
@ConfigurationProperties(prefix = "management.datasource")
public DataSource dataSource() {
    return DataSourceBuilder.create().build();
}

Properties should look like the following. Notice the @ConfigurationProperties with prefix. The prefix is everything before the actual property name

management.datasource.test-on-borrow=true
management.datasource.validation-query=SELECT 1

A reference for Spring Version 1.4.4.RELEASE

回答7:

whoami's answer is the correct one. Using the properties as suggested I was unable to get this to work (using Spring Boot 1.5.3.RELEASE)

I'm adding my answer since it's a complete configuration class so it might help someone using Spring Boot:

@Configuration
@Log4j
public class SwatDataBaseConfig {

    @Value("${swat.decrypt.location}")
    private String fileLocation;

    @Value("${swat.datasource.url}")
    private String dbURL;

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

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

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

    @Bean
    public DataSource primaryDataSource() {
        PoolProperties poolProperties = new PoolProperties();
        poolProperties.setUrl(dbURL);
        poolProperties.setUsername(userName);
        poolProperties.setPassword(password);
        poolProperties.setDriverClassName(driverName);
        poolProperties.setTestOnBorrow(true);
        poolProperties.setValidationQuery("SELECT 1");
        poolProperties.setValidationInterval(0);
        DataSource ds = new org.apache.tomcat.jdbc.pool.DataSource(poolProperties);
        return ds;
    }
}