java - 在 c3p0 池中检查连接

标签 java hibernate c3p0 socketexception

我正在开发 Java SE 应用程序，使用 Hibernate 4 和 c3p0 与 MariaDB 数据库进行通信。这是一个长时间运行的应用程序，等待来自外部的信号，因此有时数据库会在 8 小时不活动后关闭我的连接。我尝试配置 c3p0 连接验证，但它不起作用。你能帮帮我吗？

错误日志(命名查询执行期间抛出):

2014-10-27 08:10:19.062 ERROR [trans] com.example.runnable.T1 - Exception thrown during event processing, rollbacking transaction: org.hibernate.exception.JDBCConnectionException: could not extract ResultSet
        at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:132)
        at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
        at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:91)
        at org.hibernate.loader.Loader.getResultSet(Loader.java:2065)
        at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1862)
        at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1838)
        at org.hibernate.loader.Loader.doQuery(Loader.java:909)
        at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354)
        at org.hibernate.loader.Loader.doList(Loader.java:2553)
        at org.hibernate.loader.Loader.doList(Loader.java:2539)
        at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2369)
        at org.hibernate.loader.Loader.list(Loader.java:2364)
        at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:496)
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387)
        at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:231)                                                                                                                                                    
        at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1264)                                                                                                                                                                    
        at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)                                                                                                                                                                         
        at com.example.runnable.T1.find(EventsTransmitter.java:140)                                                                                                                         
        at com.example.runnable.T1.run(EventsTransmitter.java:86)                                                                                                                                  
        at java.lang.Thread.run(Thread.java:745)                                                                                                                                                                                             
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 108,132,692 milliseconds ago.  The last packet sent successfully to the server was 108,132,692 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.                                                                                                                                                              
        at sun.reflect.GeneratedConstructorAccessor30.newInstance(Unknown Source)                                                                                                                                                            
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)                                                                                                                              
        at java.lang.reflect.Constructor.newInstance(Constructor.java:408)                                                                                                                                                                   
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)                                                                                                                                                                              
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1036)                                                                                                                                                         
        at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3661)                                                                                                                                                                                    
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2417)                                                                                                                                                                             
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2582)                                                                                                                                                                          
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2530)                                                                                                                                                                   
        at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1907)                                                                                                                                                     
        at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2030)                                                                                                                                                        
        at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:82)                                                                                                                                       
        ... 17 more                                                                                                                                                                                                                          
Caused by: java.net.SocketException: Broken pipe                                                                                                                                                                                             
        at java.net.SocketOutputStream.socketWrite0(Native Method)                                                                                                                                                                           
        at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
        at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
        at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
        at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
        at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3643)
        ... 23 more

pom.xml:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.33</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>4.3.6.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>5.1.2.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>4.3.1.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-ehcache</artifactId>
    <version>4.3.6.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-c3p0</artifactId>
    <version>4.3.6.Final</version>
</dependency>

src/main/resources/hibernate.cfg.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/MyBase?zeroDateTimeBehavior=convertToNull&amp;autoReconnect=true</property>
    <property name="hibernate.connection.username">user</property>
    <property name="hibernate.connection.password">pass</property>

    <property name="hibernate.current_session_context_class">thread</property>

    <property name="show_sql">true</property>
    <property name="use_sql_comments">true</property>

    <property name="hibernate.cache.use_second_level_cache">true</property>
    <property name="hibernate.cache.use_query_cache">true</property>
    <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>

    <property name="hibernate.c3p0.min_size">5</property>
    <property name="hibernate.c3p0.max_size">10</property>
    <property name="hibernate.c3p0.timeout">300</property>
    <property name="hibernate.c3p0.max_statements">30</property>

    <mapping class="com.example.domain.E" />
    </session-factory>
</hibernate-configuration>

src/main/resources/c3p0-config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
    <property name="preferredTestQuery">SELECT 1 FROM DUAL</property>
    <property name="testConnectionOnCheckin">true</property>
    <property name="idleConnectionTestPeriod">1800</property> <!-- 30 minutes -->
    </default-config>
</c3p0-config>

已编辑

在启动日志中，我得到了 c3p0 配置(由 Maven 从 Netbeans 执行):

...
INFO: Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@81187ff9
[ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@e1820e10 [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000,
autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null,
connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> false, factoryClassLocation -> null,
forceIgnoreUnresolvedTransactions -> false, identityToken -> z8kflt95n558v5xddgsj|2cf3d63b, idleConnectionTestPeriod -> 1800, initialPoolSize -> 5,
maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 300, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 10, maxStatements -> 30,
maxStatementsPerConnection -> 0, minPoolSize -> 5, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@2f0d7eae [ description -> null, driverClass -> null,
factoryClassLocation -> null, identityToken -> z8kflt95n558v5xddgsj|1e6a3214, jdbcUrl -> jdbc:mysql://localhost:3306/MyBase?zeroDateTimeBehavior=convertToNull&autoReconnect=true,
properties -> {user=******, password=******} ], preferredTestQuery -> SELECT 1 FROM DUAL, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0,
testConnectionOnCheckin -> true, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ],
dataSourceName -> null, factoryClassLocation -> null, identityToken -> z8kflt95n558v5xddgsj|7161d8d1, numHelperThreads -> 3 ]
...

编辑2

当执行由 maven-shade-plugin 创建的 jar 时，我得到:

paź 27, 2014 10:56:22 PM org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator instantiateC3p0Provider WARN: HHH000022: c3p0 properties were encountered, but the c3p0 provider class was not found on the classpath; these properties are going to be ignored. paź 27, 2014 10:56:22 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!) paź 27, 2014 10:56:22 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator

或者当我试图在属性中指示 org.hibernate.connection.C3P0ConnectionProvider 时:

INFO: HHH000130: Instantiating explicit connection provider: org.hibernate.connection.C3P0ConnectionProvider Initial SessionFactory creation failed.org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.connections.spi.ConnectionProvider] Exception in thread "main" java.lang.ExceptionInInitializerError at com.example.util.HibernateUtil.(HibernateUtil.java:27) at com.example.App.run(App.java:31) at com.example.App.main(App.java:25)
Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.connections.spi.ConnectionProvider] 

    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:261)

    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:225)

    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)

    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.buildJdbcConnectionAccess(JdbcServicesImpl.java:260)

    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:94)

    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)

    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)

    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)

    at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)

    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)

    at com.example.util.HibernateUtil.<clinit>(HibernateUtil.java:24)

    ... 2 more                                                                                                                                                                                                                Caused by: org.hibernate.HibernateException: Could not instantiate

connection provider [org.hibernate.connection.C3P0ConnectionProvider] 

    at org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator.instantiateExplicitConnectionProvider(ConnectionProviderInitiator.java:197)

    at org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator.initiateService(ConnectionProviderInitiator.java:120)
    at org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator.initiateService(ConnectionProviderInitiator.java:55)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:105)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:251)
    ... 12 more Caused by: org.hibernate.boot.registry.selector.spi.StrategySelectionException:

Unable to resolve name [org.hibernate.connection.C3P0ConnectionProvider] as strategy [org.hibernate.engine.jdbc.connections.spi.ConnectionProvider] at org.hibernate.boot.registry.selector.internal.StrategySelectorImpl.selectStrategyImplementor(StrategySelectorImpl.java:128) at org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator.instantiateExplicitConnectionProvider(ConnectionProviderInitiator.java:194) ... 16 more

但是当由 Maven 启动时一切都很好。不幸的是，我需要这个才能从单个 jar 中工作。为什么在 shaded jar 中找不到 org.hibernate.connection.C3P0ConnectionProvider 有什么想法吗？

最佳答案

好的，我设法解决了所有问题。这是灵魂。

首先，正如 Steve Waldman 所建议的，c3p0 实际上并没有被初始化，但是在 Hibernate 4.3 中 hibernate.connection.provider_class 参数应该是:org.hibernate.c3p0.internal。 C3P0ConnectionProvider。在 documentation你可以阅读:

A connection provider that uses a C3P0 connection pool. Hibernate will use this by default if the hibernate.c3p0.* properties are set.

但在我看来，最好自己设置此参数，如果您使用的是 c3p0 配置文件而不是 hibernate.c3p0.* 属性，则需要它。

第二个问题是通过在线程开始时调用 SessionFactory.openSession() 获取 session ，然后始终使用相同的 session 对象。我想在数据库连接断开后，池中重新创建了一个新连接，使用旧 session 导致使用旧的、断开的连接。因此，可能的解决方案是在捕获连接错误后通过 SessionFactory.openSession() 获取新 session ，或者在每次通信开始时使用 SessionFactory.getCurrentSession()。我决定使用第二个选项(在这种情况下，我的应用程序等待外部信号，有时会等待数小时，因此我在每个信号后获取当前 session )。

我的最终配置:

hibernate .cfg.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/MyBase?zeroDateTimeBehavior=convertToNull&amp;autoReconnect=true</property>
    <property name="hibernate.connection.username">user</property>
    <property name="hibernate.connection.password">pass</property>
    <property name="hibernate.connection.provider_class">org.hibernate.c3p0.internal.C3P0ConnectionProvider</property>

    <property name="hibernate.current_session_context_class">thread</property>

    <property name="show_sql">true</property>
    <property name="use_sql_comments">true</property>

    <property name="hibernate.cache.use_second_level_cache">true</property>
    <property name="hibernate.cache.use_query_cache">true</property>
    <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
    </session-factory>
</hibernate-configuration>

c3p0-config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
    <property name="initialPoolSize">5</property>
    <property name="minPoolSize">5</property>
    <property name="maxPoolSize">10</property>
    <property name="checkoutTimeout">3000</property>
    <property name="maxStatementsPerConnection">30</property>

    <property name="preferredTestQuery">SELECT 1 FROM DUAL</property>
    <property name="testConnectionOnCheckin">true</property>
    <property name="testConnectionOnCheckout">false</property>
    <property name="idleConnectionTestPeriod">300</property> <!-- 5 minutes -->
    </default-config>
</c3p0-config>

使用这个 c3p0 配置:

  • 每隔 5 分钟不对连接执行任何查询，它将被测试一次，因此它永远不会被 DB 失效(在标准配置中，MySQL 会在 8 小时不活动后使连接失效)，
  • 如果要重启数据库或手动终止连接，我们有两个选择: a) 最多 5 分钟后将重新建立连接， b) 如果应用程序在自动连接重新建立之前尝试执行查询，将抛出 HibernateException，然后重新建立连接，下一次查询将成功。

可以选择将 testConnectionOnCheckout 设置为 true 以防止异常，但这会导致性能问题(参见 documentation )。

关于java - 在 c3p0 池中检查连接，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26583120/

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