我是休眠的新手,已经开始使用C3P0作为休眠的连接池管理器,因为没有它,在与MySQL服务器没有联系8个小时之后,我遇到了超时问题。
切换到C3P0后,我最近遇到了死锁,我不确定它是如何发生的。我虽然显示了所有堆栈跟踪和配置。
这是配置日志
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$5.doPrepare(StatementPreparerImpl.java:162) at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$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$2(DefaultRequestManager.java:103) at com.game.server.manager.request.DefaultRequestManager$$Lambda$63/869031346.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$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。
您的应用程序几乎肯定会泄漏连接。有关如何调试问题,请参见c3p0的文档。
TL; DR:设置
<property name="hibernate.c3p0.unreturnedConnectionTimeout">30</property> <property name="hibernate.c3p0.debugUnreturnedConnectionStackTraces">true</property>
Check your logs for stack traces that check out Connections or Sessions in your application but fail to reliably close() them. Fix that, by using something like try-with-resources to reliably close things. When you have fixed the problem, remove the above properties.
See also this