在使用C3P0、OneJar和MySQL时遇到致命故障

Question

在使用C3P0、OneJar和MySQL C3P0设置时会出现致命故障，如下所示：

pooledDataSource=new ComboPooledDataSource();
            set database properies ie userName password driver etc

            pooledDataSource.setMaxPoolSize(100);
            pooledDataSource.setMinPoolSize(10);
            pooledDataSource.setInitialPoolSize(10);
            pooledDataSource.setAcquireIncrement(4);

            pooledDataSource.setIdleConnectionTestPeriod(900);
            pooledDataSource.setTestConnectionOnCheckin(true);

            pooledDataSource.setMaxIdleTimeExcessConnections(300);

            pooledDataSource.setNumHelperThreads(6);
            pooledDataSource.setMaxAdministrativeTaskTime(60);

            pooledDataSource.setUnreturnedConnectionTimeout(120);
            pooledDataSource.setDebugUnreturnedConnectionStackTraces(true);



**Thread Dump is as follows**



Found one Java-level deadlock:
=============================
"com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#3":
  waiting to lock monitor 0x00007f443abe32a0 (object 0x00000000c6071690, a com.simontuffs.onejar.JarClassLoader),
  which is held by "main"
"main":
  waiting to lock monitor 0x00007f443abe2b68 (object 0x00000000c615e950, a com.simontuffs.onejar.JarClassLoader$1),
  which is held by "com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#3"

Java stack information for the threads listed above:
===================================================
"com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#3":
    at java.lang.ClassLoader.loadClass(ClassLoader.java:403)
    - waiting to lock <0x00000000c6071690> (a com.simontuffs.onejar.JarClassLoader)
    at com.simontuffs.onejar.JarClassLoader.loadClass(JarClassLoader.java:630)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:410)
    - locked <0x00000000c615e950> (a com.simontuffs.onejar.JarClassLoader$1)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at com.simontuffs.onejar.JarClassLoader$1.loadClass(JarClassLoader.java:296)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    - locked <0x00000000c615e950> (a com.simontuffs.onejar.JarClassLoader$1)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at com.simontuffs.onejar.JarClassLoader$1.loadClass(JarClassLoader.java:296)
    at com.mysql.jdbc.DatabaseMetaData$9.forEach(DatabaseMetaData.java:5276)
    at com.mysql.jdbc.DatabaseMetaData$9.forEach(DatabaseMetaData.java:5239)
    at com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:50)
    at com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:5238)
    at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
    at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
    at com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishResourceOnCheckin(C3P0PooledConnectionPool.java:301)
    at com.mchange.v2.resourcepool.BasicResourcePool.attemptRefurbishResourceOnCheckin(BasicResourcePool.java:1606)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$200(BasicResourcePool.java:32)
    at com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1228)
    at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
"main":
    at java.lang.ClassLoader.loadClass(ClassLoader.java:403)
    - waiting to lock <0x00000000c615e950> (a com.simontuffs.onejar.JarClassLoader$1)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at com.simontuffs.onejar.JarClassLoader$1.loadClass(JarClassLoader.java:296)
    at com.simontuffs.onejar.JarClassLoader.findClass(JarClassLoader.java:642)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    - locked <0x00000000c6071690> (a com.simontuffs.onejar.JarClassLoader)
    at com.simontuffs.onejar.JarClassLoader.loadClass(JarClassLoader.java:630)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at org.hibernate.cfg.SettingsFactory.createBatcherFactory(SettingsFactory.java:443)
    at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:195)
    at org.hibernate.cfg.Configuration.buildSettingsInternal(Configuration.java:2863)
    at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2859)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1870)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:906)
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:74)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:268)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:310)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1514)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1452)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
    - locked <0x00000000fa3ce208> (a java.util.concurrent.ConcurrentHashMap)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:591)
    - locked <0x00000000fa3ce258> (a java.util.concurrent.ConcurrentHashMap)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:469)
    - locked <0x00000000fa3ce358> (a java.lang.Object)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
    at com.goldensource.activegateway.backoffice.launcher.BackOfficeJobLauncher.sendNotification(BackOfficeJobLauncher.java:464)
    at com.goldensource.activegateway.backoffice.launcher.BackOfficeJobLauncher.main(BackOfficeJobLauncher.java:186)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.simontuffs.onejar.Boot.run(Boot.java:340)
    at com.simontuffs.onejar.Boot.main(Boot.java:166)

Found 1 deadlock.

但是当我使用jtd连接到SQL数据库时，每件事都能正常工作吗？有人能告诉我出了什么问题吗？

Answer 1

因此，这看起来像是C3P0的帮助线程试图使用OneJar类加载器加载类的问题。尝试更新到c3p0-0.9.5 (当前为c3p0-0.9.5-pre6)的最新预发布版本，并将配置属性contextClassLoaderSource设置为library或none。请参阅http://www.mchange.com/projects/c3p0/#contextClassLoaderSource