hibernate+spring中连接池c3p0不能释放连接

[qwerasdf123]

如题:
application.xml连接池配置:

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="driverClass" value="com.mysql.jdbc.Driver"></property>
		<property name="jdbcUrl">
		    <value>jdbc:mysql://localhost/icrom?useUnicode=true&characterEncoding=utf-8</value>		</property>
		<property name="user">
                      <value>root</value>
		</property>
		<property name="password">
		    <value>12345678</value>
		</property>
		<property name="minPoolSize">
		    <value>5</value>
		</property>
		<property name="maxPoolSize">
		    <value>30</value>
		</property>
		<property name="initialPoolSize">
		    <value>10</value>
		</property>
		<property name="maxIdleTime">
		    <value>60</value>
		</property>
		<property name="acquireIncrement">
		    <value>3</value>
		</property>
		<property name="maxStatements">
            <value>0</value>
        </property>
        <property name="maxStatementsPerConnection">
        	<value>0</value>
        </property> 
        <property name="idleConnectionTestPeriod">
            <value>28680</value>
        </property>
        <property name="acquireRetryAttempts">
            <value>30</value>
        </property>
        <property name="breakAfterAcquireFailure">
            <value>false</value>
        </property>
        <property name="testConnectionOnCheckout">
            <value>false</value>
        </property>
	</bean>

程序中使用查询部分的代码:

public AbstractPersistentObject findById(Class<?> klass, Integer id) {
        log.debug("getting " + klass.getName() + " instance with id: " + id);
        try {
            AbstractPersistentObject instance = (AbstractPersistentObject) 
                    getHibernateTemplate()
                    .get(klass, id);
            return instance;
        } catch (RuntimeException re) {
            log.error("get failed", re);
            throw re;
        }
    }

结果是每查询30次就一直阻塞在那里了,因为连接池的连接已经用完了!显示的日志是:
opening JDBC connection
acquire test -- pool size: 29; target_pool_size: 29; desired target? 30
incremented pending_acquires: 1
awaitAvailable(): com.mchange.v2.c3p0.impl.NewPooledConnection@280bca
trace com.mchange.v2.resourcepool.BasicResourcePool@6c01b9 [managed: 29, unused: 0, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@280bca)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$[e-mail]() returning.
trace com.mchange.v2.resourcepool.BasicResourcePool@6c01b9 [managed: 30, unused: 1, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@280bca)
decremented pending_acquires: 0
trace com.mchange.v2.resourcepool.BasicResourcePool@6c01b9 [managed: 30, unused: 0, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@280bca)
.
.
.
.
initializing non-lazy collections
after autocommit
transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources!
after transaction completion
Eagerly flushing Hibernate session
flushing session
processing flush-time cascades
dirty checking collections
Flushing entities and processing referenced collections
Processing unreferenced collections
Scheduling collection removes/(re)creates/updates
Flushed: 0 insertions, 0 updates, 0 deletions to 1 objects
Flushed: 0 (re)creations, 0 updates, 0 removals to 0 collections
listing entities:
cn.icrom.biz.datapackage.news.object.NEWS_DATA_EXISTS{id=component[ID,DATA_FID,KODE,PUBLISH_DATE]{DATA_FID=9340, KODE=33cca49be6f395c739fa793b6bba0f5d, PUBLISH_DATE=2010-03-25 00:00:00, ID=9334}}
executing flush
registering flush begin
registering flush end
post flush
Registering Hibernate Session for deferred close
setting flush mode to: NEVER
Read class cn.icrom.biz.datapackage.news.object.NEWS_DATA detail data.
Returning cached instance of singleton bean 'BaseHibernateDAO'
getting cn.icrom.biz.datapackage.news.object.NEWS_DATA instance with id: 9340
Opening Hibernate Session
opened session at timestamp: 12754676400
loading entity: [cn.icrom.biz.datapackage.news.object.NEWS_DATA#9340]
attempting to resolve: [cn.icrom.biz.datapackage.news.object.NEWS_DATA#9340]
object not resolved in any cache: [cn.icrom.biz.datapackage.news.object.NEWS_DATA#9340]
Fetching entity: [cn.icrom.biz.datapackage.news.object.NEWS_DATA#9340]
loading entity: [cn.icrom.biz.datapackage.news.object.NEWS_DATA#9340]
about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
opening JDBC connection
acquire test -- pool is already maxed out. [managed: 30; max: 30]


求解呀!
请教对这连接池比较了解的朋友,怎么来解决这问题?是哪里有问题的呢?

[qunhao]

我前段时间也遇到过这个问题。
我后来检查发现，原来是程序中获取session进行操作后没有关闭，导致占用数据库连接没有释放。后来用完session把它给close了，就不再出现这个问题了。
说明一下：如果有用spring的声明式事务的话，那么通过this.getSesson()获取到的session是不需要关闭的，spring的事务会去管理。

楼主你的问题好像也应该差不多是这样
英文我看不太懂，不过我估计你的错误信息中下面这一句是关键，你从这入手去查查。
transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources!

[qwerasdf123]

这个关闭连接不是由连接池管理的吗!
我这里使用的是C3PO连接池管理这些连接,的
我这应用并没有使用声明式事务,
这种情况下SPRING,或者c3p0不会自己去关闭连接吗!?

[zhanlang9075]

1。你的配置信息是配置在spring主配置文件里的，所以spring会帮你关闭数据库连接
2。spring会在c3p0被使用后的基础上进行关闭。

[qwerasdf123]

我也是这么想的!但就是不知道为什么!我使用这查询后就是不生释放这连接,然后程序循环使用了
30次后就报错说没有连接可以使用了!
不知道原因呀!

[qwerasdf123]

问题已经解决，原来在配置hibernater时少配了一个属性：
<prop key="hibernate.connection.release_mode">after_statement</prop>
唉！不懂是此属性值默认是on_close，就是session.close();时关闭连接，但我在调用这查询时，使用手动session.close();还是一样的结果。。。。

[shanxisxx]

的撒发生

[gy132]

[Quote=引用 5 楼 qwerasdf123 的回复:]
问题已经解决，原来在配置hibernater时少配了一个属性：
<prop key="hibernate.connection.release_mode">after_statement</prop>
唉！不懂是此属性值默认是on_close，就是session.close();时关闭连接，但我在调用这查询时，使用手动session.close();还是一样的结果。。。。
[/Quote]
根据你的答案，我已经解决了我认为是非常苦恼的疑难杂证，
求大神指点。。你是肿么分析的问题呢。。。。按我的解决问题模式先搜索，如未果，就有郁闷了。。。

[nookiehuihui]

lz的方法管用，我也碰到这样的问题，谢谢了，但还是不明白我手动关闭了session，sessionFactory，但数据库的链接还是满了