Hibernate 中的 c3p0 死锁
c3p0 deadlocks in Hibernate
我是 hibernate 的新手，已经开始使用 C3P0 作为 hibernate 的连接池管理器，因为如果没有它，我在 8 小时没有与 MySQL 服务器联系后遇到超时问题。
切换到 C3P0 后，我最近遇到了死锁，我不确定它是怎么发生的。我虽然有所有的堆栈跟踪和配置要显示。
这里是配置日志
Jan 27, 2017 5:56:23 PM com.mchange.v2.log.MLog <clinit>
INFO: MLog clients using java 1.4+ standard logging.
Jan 27, 2017 5:56:23 PM com.mchange.v2.c3p0.C3P0Registry banner
INFO: Initializing c3p0-0.9.2.1 [built 20-March-2013 10:47:27 +0000; debug? true; trace: 10]
Jan 27, 2017 5:56:23 PM com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
INFO: Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@28c81cce [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@35af8b6c [ acquireIncrement -> 1, 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 -> 1hge14z9l1qg67m9nxywg8|c2db68f, idleConnectionTestPeriod -> 300, initialPoolSize -> 1, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 120, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 25, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 1, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@2e47880e [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge14z9l1qg67m9nxywg8|1b765a2c, jdbcUrl -> jdbc:mysql://localhost/Pokemon_Blaze_Online_Dev, properties -> {user=******, password=******} ], preferredTestQuery -> select 1;, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge14z9l1qg67m9nxywg8|7e276594, numHelperThreads -> 3 ]
这是我设置的属性
<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">300</property>
<property name="hibernate.c3p0.timeout">120</property>
<property name="hibernate.c3p0.max_size">25</property>
<property name="hibernate.c3p0.min_size">1</property>
<property name="hibernate.c3p0.max_statement">0</property>
<property name="hibernate.c3p0.preferredTestQuery">select 1;</property>
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
这是被锁定的线程之一的线程转储。
"Request Pool-0" #71 prio=5 os_prio=0 tid=0x000000002b2df800 nid=0x1d48 in Object.wait() [0x000000003113e000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1414)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:606)
- locked <0x00000006c1b3c088> (a com.mchange.v2.resourcepool.BasicResourcePool)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:526)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:755)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:682)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
at org.hibernate.c3p0.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:90)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:387)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:228)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:171)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:63)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.doPrepare(StatementPreparerImpl.java:162)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:186)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:160)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1884)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1861)
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.criteria.CriteriaLoader.list(CriteriaLoader.java:126)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1682)
at org.hibernate.internal.CriteriaImpl.list(CriteriaImpl.java:380)
at org.hibernate.internal.CriteriaImpl.uniqueResult(CriteriaImpl.java:402)
at com.game.server.persistence.services.player.PlayerDataServiceImpl.areValidCredentials(PlayerDataServiceImpl.java:28)
at com.game.server.manager.request.service.DefaultLoginService.login(DefaultLoginService.java:78)
at com.game.server.manager.request.DefaultRequestManager.lambda$login(DefaultRequestManager.java:103)
at com.game.server.manager.request.DefaultRequestManager$$Lambda/869031346.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Locked ownable synchronizers:
- <0x000000079eea0890> (a java.util.concurrent.ThreadPoolExecutor$Worker)
由于我对此并不陌生，因此无法从日志和转储中识别问题。我还注意到 C3P0 创建了很多线程。
您的应用程序几乎可以肯定正在泄漏连接。请参阅 c3p0's docs 了解如何调试问题。
TL; DR: 设置
<property name="hibernate.c3p0.unreturnedConnectionTimeout">30</property>
<property name="hibernate.c3p0.debugUnreturnedConnectionStackTraces">true</property>
检查您的日志以查找检查应用程序中的连接或会话但无法可靠地关闭 () 它们的堆栈跟踪。通过使用 try-with-resources 之类的东西来可靠地关闭事物来解决这个问题。解决问题后，删除上述属性。
另见
我遇到过一次死锁，这些日志：
BasicResourcePool - 获取测试 -- 池已满。 [管理：10；最大值：10]
事实证明，我有一种方法启动会话+事务调用另一种方法，该方法也“获取了自己的会话”并使用了它。嵌套会话+多线程->死锁。 FWIW.
也很有用：jstack 您的应用程序（或同等应用程序），您可能会发现一些线程卡在某一点，一些线程卡在另一点......现有的阻塞线程可能正在适当地保持他们的（当前）会话......
我是 hibernate 的新手，已经开始使用 C3P0 作为 hibernate 的连接池管理器，因为如果没有它，我在 8 小时没有与 MySQL 服务器联系后遇到超时问题。
切换到 C3P0 后，我最近遇到了死锁，我不确定它是怎么发生的。我虽然有所有的堆栈跟踪和配置要显示。
这里是配置日志
Jan 27, 2017 5:56:23 PM com.mchange.v2.log.MLog <clinit>
INFO: MLog clients using java 1.4+ standard logging.
Jan 27, 2017 5:56:23 PM com.mchange.v2.c3p0.C3P0Registry banner
INFO: Initializing c3p0-0.9.2.1 [built 20-March-2013 10:47:27 +0000; debug? true; trace: 10]
Jan 27, 2017 5:56:23 PM com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
INFO: Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@28c81cce [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@35af8b6c [ acquireIncrement -> 1, 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 -> 1hge14z9l1qg67m9nxywg8|c2db68f, idleConnectionTestPeriod -> 300, initialPoolSize -> 1, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 120, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 25, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 1, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@2e47880e [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge14z9l1qg67m9nxywg8|1b765a2c, jdbcUrl -> jdbc:mysql://localhost/Pokemon_Blaze_Online_Dev, properties -> {user=******, password=******} ], preferredTestQuery -> select 1;, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge14z9l1qg67m9nxywg8|7e276594, numHelperThreads -> 3 ]
这是我设置的属性
<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">300</property>
<property name="hibernate.c3p0.timeout">120</property>
<property name="hibernate.c3p0.max_size">25</property>
<property name="hibernate.c3p0.min_size">1</property>
<property name="hibernate.c3p0.max_statement">0</property>
<property name="hibernate.c3p0.preferredTestQuery">select 1;</property>
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
这是被锁定的线程之一的线程转储。
"Request Pool-0" #71 prio=5 os_prio=0 tid=0x000000002b2df800 nid=0x1d48 in Object.wait() [0x000000003113e000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1414)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:606)
- locked <0x00000006c1b3c088> (a com.mchange.v2.resourcepool.BasicResourcePool)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:526)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:755)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:682)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
at org.hibernate.c3p0.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:90)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:387)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:228)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:171)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:63)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.doPrepare(StatementPreparerImpl.java:162)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:186)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:160)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1884)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1861)
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.criteria.CriteriaLoader.list(CriteriaLoader.java:126)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1682)
at org.hibernate.internal.CriteriaImpl.list(CriteriaImpl.java:380)
at org.hibernate.internal.CriteriaImpl.uniqueResult(CriteriaImpl.java:402)
at com.game.server.persistence.services.player.PlayerDataServiceImpl.areValidCredentials(PlayerDataServiceImpl.java:28)
at com.game.server.manager.request.service.DefaultLoginService.login(DefaultLoginService.java:78)
at com.game.server.manager.request.DefaultRequestManager.lambda$login(DefaultRequestManager.java:103)
at com.game.server.manager.request.DefaultRequestManager$$Lambda/869031346.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Locked ownable synchronizers:
- <0x000000079eea0890> (a java.util.concurrent.ThreadPoolExecutor$Worker)
由于我对此并不陌生，因此无法从日志和转储中识别问题。我还注意到 C3P0 创建了很多线程。
您的应用程序几乎可以肯定正在泄漏连接。请参阅 c3p0's docs 了解如何调试问题。
TL; DR: 设置
<property name="hibernate.c3p0.unreturnedConnectionTimeout">30</property>
<property name="hibernate.c3p0.debugUnreturnedConnectionStackTraces">true</property>
检查您的日志以查找检查应用程序中的连接或会话但无法可靠地关闭 () 它们的堆栈跟踪。通过使用 try-with-resources 之类的东西来可靠地关闭事物来解决这个问题。解决问题后，删除上述属性。
另见
我遇到过一次死锁，这些日志：
BasicResourcePool - 获取测试 -- 池已满。 [管理：10；最大值：10]
事实证明，我有一种方法启动会话+事务调用另一种方法，该方法也“获取了自己的会话”并使用了它。嵌套会话+多线程->死锁。 FWIW.
也很有用：jstack 您的应用程序（或同等应用程序），您可能会发现一些线程卡在某一点，一些线程卡在另一点......现有的阻塞线程可能正在适当地保持他们的（当前）会话......