Spring和MySQL连接（保留使用睡眠连接创建新连接，而不是使用连接）

Question

I don't know why each time someone visits a page on my website, a new connection is open to the database. Eventually I reach like 300 and get an error and pages no longer load. I thought the way it should work is, I Have maxIdle set for 30, so that means I should not have more than 30 sleeping connections open by Spring. But at this moment I have 88 open. If I close down or reboot my server it will go back down to near 0. I use getJdbcTemplate() for every query.

Here is part of my spring-config.xml

<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="XXXXXXXXX" />
    <property name="username" value="XXXXXXXXXX" />
    <property name="password" value="XXXXXXXX" />
    <property name="maxIdle" value="30"/>
    <property name="defaultAutoCommit" value="true"/>
</bean>

Here is what part the dao looks like (renamed)

@Repository
public class ExampleDAOImpl extends JdbcDaoSupport implements ExampleDAO {

@Autowired
public ExampleDAOImpl(DataSource dataSource) {
    setDataSource(dataSource);
}

Here is what I get from show processlist in MySQL (not display all rows here, there were 88)

+----------+------------+-------------------------------------------+------+---------+-------+----------------+---------------------
| Id       | User       | Host                                      | db   | Command | Time  | State          | Info             db
+----------+------------+-------------------------------------------+------+---------+-------+----------------+-----------------------
| 21721763 | user | XXXXXXXX:60586 | db | Sleep   | 10609 |                | NULL             db
| 21924432 | user | XXXXXXXX:59498 | db | Query   |     0 | NULL           | show processlist db
| 21924580 | user | XXXXXXXX:59702 | db | Sleep   |   790 |                | NULL             db
| 21924722 | user | XXXXXXXX:60010 | db | Sleep   |   790 |                | NULL             db
| 21924813 | user | XXXXXXXX:60131 | db | Sleep   |   787 |                | NULL             db
| 21924819 | user | XXXXXXXX:60139 | db | Sleep   |   786 |                | NULL             db
| 21924841 | user | XXXXXXXX:60156 | db | Sleep   |   785 |                | NULL             db
| 21927089 | user | XXXXXXXX:56292 | db | Query   |     1 | Opening tables | XXXXXXXX |
| 21927090 | user | XXXXXXXX:56295 | db | Query   |     1 | Opening tables | XXXXXXXX |
88 rows in set (0.01 sec)

Example dao method

public String selectSomething(String text) throws IllegalArgumentException, DAOException {
     return (String) getJdbcTemplate().queryForObject(SELECT_QUERY_1, new Object[] {text}, String.class);
}

Answer 1

Try this configuration, which is the result of many tweaks for a PROD environment:

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver">
        <property name="url" value="XXX" />
        <property name="username" value="XXX"/>
        <property name="password" value="XXX"/>
        <property name="minIdle" value="0"/>
        <property name="maxIdle" value="10"/>
        <property name="maxActive" value="50"/>
        <property name="maxWait" value="60000"/>
        <property name="testOnBorrow" value="true"/>
        <property name="validationQuery" value="SELECT 1"/>               
        <property name="timeBetweenEvictionRunsMillis" value="1800000"/>
        <property name="numTestsPerEvictionRun" value="50"/>
        <property name="minEvictableIdleTimeMillis" value="10"/>
        <property name="testWhileIdle" value="true"/>
    </bean>