尝试在后台线程中获取缓存的 PreparedStatement 时发生错误答案

【问题标题】：Error occured while trying to acquire a cached PreparedStatement in a background thread尝试在后台线程中获取缓存的 PreparedStatement 时发生错误
【发布时间】：2017-03-07 05:00:52
【问题描述】：

我们正在使用数据库组件中的 mule 提供的连接池。当我们施加巨大的负载时，我们会遇到错误。

配置参数为：maxConnection=100, minConn=0, autoIncrement =15 waitMillisec=10000 并且准备好的语句缓存大小保持默认（即没有配置任何东西）。能否请您协助解决以下问题。

{"timestamp":"2016-10-22T09:28:13,611","level":"WARN","thread":"ActiveMQ Session Task-25","loggerName":"com.mchange.v2.c3p0.impl.NewPooledConnection","message":"[c3p0] A PooledConnection that has already signalled a Connection error is still in use!"}    
{"timestamp":"2016-10-22T09:28:13,611","level":"WARN","thread":"ActiveMQ Session Task-25","loggerName":"com.mchange.v2.c3p0.impl.NewPooledConnection","message":"[c3p0] Another error has occurred [ java.sql.SQLException: A problem occurred while trying to acquire a cached PreparedStatement in a background thread. ] which will not be reported to listeners!"}
    java.sql.SQLException: A problem occurred while trying to acquire a cached PreparedStatement in a background thread.
        at com.mchange.v2.c3p0.stmt.GooGooStatementCache.acquireStatement(GooGooStatementCache.java:571) ~[?:?]
        at com.mchange.v2.c3p0.stmt.GooGooStatementCache.checkoutStatement(GooGooStatementCache.java:204) ~[?:?]
        at com.mchange.v2.c3p0.impl.NewPooledConnection.checkoutStatement(NewPooledConnection.java:321) ~[?:?]
        at com.mchange.v2.c3p0.impl.NewProxyConnection.prepareStatement(NewProxyConnection.java:455) ~[?:?]
        at org.mule.module.db.internal.domain.connection.DefaultDbConnection.prepareStatement(DefaultDbConnection.java:52) ~[?:?]
        at org.mule.module.db.internal.domain.autogeneratedkey.NoAutoGeneratedKeyStrategy.prepareStatement(NoAutoGeneratedKeyStrategy.java:34) ~[?:?]
        at org.mule.module.db.internal.domain.statement.QueryStatementFactory.create(QueryStatementFactory.java:59) ~[?:?]
        at org.mule.module.db.internal.domain.executor.AbstractSingleQueryExecutor.execute(AbstractSingleQueryExecutor.java:44) ~[?:?]
        at org.mule.module.db.internal.processor.UpdateMessageProcessor.doExecuteQuery(UpdateMessageProcessor.java:59) ~[?:?]
        at org.mule.module.db.internal.processor.AbstractSingleQueryDbMessageProcessor.executeQuery(AbstractSingleQueryDbMessageProcessor.java:42) ~[?:?]
        at org.mule.module.db.internal.processor.AbstractDbMessageProcessor.process(AbstractDbMessageProcessor.java:66) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:88) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:80) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:50) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.access$001(InterceptingChainLifecycleWrapper.java:22) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper$1.process(InterceptingChainLifecycleWrapper.java:66) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:61) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:88) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:80) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:98) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:98) ~[?:?]
        at org.mule.construct.DynamicPipelineMessageProcessor.process(DynamicPipelineMessageProcessor.java:55) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:88) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:80) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:98) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:98) ~[?:?]
        at org.mule.interceptor.AbstractEnvelopeInterceptor.processBlocking(AbstractEnvelopeInterceptor.java:58) ~[?:?]
        at org.mule.processor.AbstractRequestResponseMessageProcessor.process(AbstractRequestResponseMessageProcessor.java:47) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:98) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:98) ~[?:?]
        at org.mule.processor.AbstractFilteringMessageProcessor.process(AbstractFilteringMessageProcessor.java:41) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:98) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:98) ~[?:?]
        at org.mule.processor.AbstractRequestResponseMessageProcessor.processBlocking(AbstractRequestResponseMessageProcessor.java:56) ~[?:?]
        at org.mule.processor.AbstractRequestResponseMessageProcessor.process(AbstractRequestResponseMessageProcessor.java:47) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.executeNext(BlockingProcessorExecutor.java:88) ~[?:?]
        at org.mule.processor.BlockingProcessorExecutor.execute(BlockingProcessorExecutor.java:59) ~[?:?]
        at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:80) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:50) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.access$001(InterceptingChainLifecycleWrapper.java:22) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper$1.process(InterceptingChainLifecycleWrapper.java:66) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:61) ~[?:?]
        at org.mule.construct.AbstractPipeline$3.process(AbstractPipeline.java:231) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.chain.SimpleMessageProcessorChain.doProcess(SimpleMessageProcessorChain.java:43) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:50) ~[?:?]
        at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:76) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.access$001(InterceptingChainLifecycleWrapper.java:22) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper$1.process(InterceptingChainLifecycleWrapper.java:66) ~[?:?]
        at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:24) ~[?:?]
        at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:107) ~[?:?]
        at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:44) ~[?:?]
        at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:61) ~[?:?]
        at org.mule.transport.AbstractMessageReceiver.routeEvent(AbstractMessageReceiver.java:511) ~[?:?]
        at org.mule.transport.AbstractMessageReceiver.routeMessage(AbstractMessageReceiver.java:226) ~[?:?]
        at org.mule.transport.AbstractMessageReceiver.routeMessage(AbstractMessageReceiver.java:208) ~[?:?]
        at org.mule.transport.AbstractReceiverWorker$1$1.process(AbstractReceiverWorker.java:145) ~[?:?]
        at org.mule.transport.AbstractReceiverWorker$1$1.process(AbstractReceiverWorker.java:113) ~[?:?]
        at org.mule.execution.ExecuteCallbackInterceptor.execute(ExecuteCallbackInterceptor.java:16) ~[?:?]
        at org.mule.execution.CommitTransactionInterceptor.execute(CommitTransactionInterceptor.java:35) ~[?:?]
        at org.mule.execution.CommitTransactionInterceptor.execute(CommitTransactionInterceptor.java:22) ~[?:?]
        at org.mule.execution.HandleExceptionInterceptor.execute(HandleExceptionInterceptor.java:30) ~[?:?]
        at org.mule.execution.HandleExceptionInterceptor.execute(HandleExceptionInterceptor.java:14) ~[?:?]
        at org.mule.execution.BeginAndResolveTransactionInterceptor.execute(BeginAndResolveTransactionInterceptor.java:67) ~[?:?]
        at org.mule.execution.ResolvePreviousTransactionInterceptor.execute(ResolvePreviousTransactionInterceptor.java:44) ~[?:?]
        at org.mule.execution.SuspendXaTransactionInterceptor.execute(SuspendXaTransactionInterceptor.java:50) ~[?:?]
        at org.mule.execution.ValidateTransactionalStateInterceptor.execute(ValidateTransactionalStateInterceptor.java:40) ~[?:?]
        at org.mule.execution.IsolateCurrentTransactionInterceptor.execute(IsolateCurrentTransactionInterceptor.java:41) ~[?:?]
        at org.mule.execution.ExternalTransactionInterceptor.execute(ExternalTransactionInterceptor.java:48) ~[?:?]
        at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:28) ~[?:?]
        at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:13) ~[?:?]
        at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:110) ~[?:?]
        at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:30) ~[?:?]
        at org.mule.transport.AbstractReceiverWorker$1.process(AbstractReceiverWorker.java:112) ~[?:?]
        at org.mule.transport.AbstractReceiverWorker$1.process(AbstractReceiverWorker.java:96) ~[?:?]
        at org.mule.execution.ExecuteCallbackInterceptor.execute(ExecuteCallbackInterceptor.java:16) ~[?:?]
        at org.mule.execution.BeginAndResolveTransactionInterceptor.execute(BeginAndResolveTransactionInterceptor.java:67) ~[?:?]
        at org.mule.execution.ResolvePreviousTransactionInterceptor.execute(ResolvePreviousTransactionInterceptor.java:44) ~[?:?]
        at org.mule.execution.SuspendXaTransactionInterceptor.execute(SuspendXaTransactionInterceptor.java:50) ~[?:?]
        at org.mule.execution.ValidateTransactionalStateInterceptor.execute(ValidateTransactionalStateInterceptor.java:40) ~[?:?]
        at org.mule.execution.IsolateCurrentTransactionInterceptor.execute(IsolateCurrentTransactionInterceptor.java:41) ~[?:?]
        at org.mule.execution.ExternalTransactionInterceptor.execute(ExternalTransactionInterceptor.java:48) ~[?:?]
        at org.mule.execution.TransactionalExecutionTemplate.execute(TransactionalExecutionTemplate.java:65) ~[?:?]
        at org.mule.transport.AbstractReceiverWorker.processMessages(AbstractReceiverWorker.java:179) ~[?:?]
        at org.mule.transport.jms.MultiConsumerJmsMessageReceiver$SubReceiver.onMessage(MultiConsumerJmsMessageReceiver.java:439) ~[?:?]
        at org.apache.activemq.ActiveMQMessageConsumer.dispatch(ActiveMQMessageConsumer.java:1394) ~[?:?]
        at org.apache.activemq.ActiveMQSessionExecutor.dispatch(ActiveMQSessionExecutor.java:131) ~[?:?]
        at org.apache.activemq.ActiveMQSessionExecutor.iterate(ActiveMQSessionExecutor.java:202) ~[?:?]
        at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:133) ~[?:?]
        at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:48) ~[?:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_73]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_73]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_73]
    Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
        at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:170) ~[?:?]
        at com.microsoft.sqlserver.jdbc.SQLServerConnection.checkClosed(SQLServerConnection.java:304) ~[?:?]
        at com.microsoft.sqlserver.jdbc.SQLServerConnection.prepareStatement(SQLServerConnection.java:1863) ~[?:?]
        at com.microsoft.sqlserver.jdbc.SQLServerConnection.prepareStatement(SQLServerConnection.java:1566) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_73]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_73]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_73]
        at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_73]
        at com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask.run(GooGooStatementCache.java:546) ~[?:?]
        at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696) ~[?:?]

【问题讨论】：

我回滚了你的标题编辑，这个标题比“数据库连接池-c3p0 in mule 3.7.3”更能描述问题

标签： jdbc mule c3p0 mule-component mule-cluster

【解决方案1】：

问题：

如果您在 Oracle 12c 12.2.0.0.0 及更高版本 和 NLS_CHARACTERSET WE8ISO8859P15 上使用 ojdbc8 并带有返回自动生成的密钥，它会产生以下错误：

Caused by: java.sql.SQLException: A problem occurred while trying to acquire a cached PreparedStatement in a background thread.
   at com.mchange.v2.c3p0.stmt.GooGooStatementCache.acquireStatement(GooGooStatementCache.java:571)
   at com.mchange.v2.c3p0.stmt.GooGooStatementCache.checkoutStatement(GooGooStatementCache.java:204)
   at com.mchange.v2.c3p0.impl.NewPooledConnection.checkoutStatement(NewPooledConnection.java:321)
   at com.mchange.v2.c3p0.impl.NewProxyConnection.prepareStatement(NewProxyConnection.java:431)
   at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$3.doPrepare(StatementPreparerImpl.java:117)
   at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
   ... 29 more
Caused by: java.sql.SQLException: Invalid argument(s) in call
   at oracle.jdbc.driver.AutoKeyInfo.getNewSql(AutoKeyInfo.java:187)
   at oracle.jdbc.driver.PhysicalConnection.prepareStatement(PhysicalConnection.java:4342)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:498)
   at com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask.run(GooGooStatementCache.java:547)
   at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)

解决方案：

有一个数据库补丁可以解决这个问题。
否则您可以将字符集更改为 WE8ISO8859P1

参考

https://support.oracle.com/knowledge/Middleware/2278611_1.html

【讨论】：

【解决方案2】：

我在保存（插入）第一个对象时遇到了 hsqldb (2.4.1) 和 hibernate (5.3.1) 的问题。

创建表 (DDL) 成功，但保存（SQL 准备语句）失败。

我没有应用命名策略，hibernate 显然创建了 SQL，其中表名的大小写与 hsqldb 预期的不匹配。

Hsqldb 是区分大小写的，虽然人们会期待一个明确的错误消息，但上面的错误被报告了。

通过添加JPA 注释@Table(name="your_table") 解决了这个问题。

【讨论】：

【解决方案3】：

好的。

如果您正在使用语句缓存，如果没有适当的缓存语句可用于连接，c3p0 会异步获取缓存的语句。在负载较重且没有仔细配置的情况下，由于服务器拥塞或 c3p0 的线程池拥塞，此异步获取可能需要很长时间。尝试获取 Statement 的客户端会无限期地等待，直到成功获取 Statement 或发生异常。

从根本原因异常（向下到堆栈跟踪的底部），很明显，虽然发生了可能很长的 Statement 获取，但要从中获取 Statement 的 Connection 已关闭（）或死亡.这就是你需要调试才能真正理解这一点。可能的原因包括：

在这些情况下，负载/网络问题/神秘的 gremlins 偶尔会破坏连接，导致它们无效并关闭（）
DBMS 或某些管理观察者关闭（）这些（可能是长时间挂起的）连接，因为打开的连接太多或打开时间过长。（也许这是死锁检测器的工作。）
您的应用程序（不明智地）在多个线程中使用连接，其中一个线程调用 close()，而另一个线程仍在等待（）语句。然后池（出于多种原因）尝试关闭（）导致此错误的签入连接。

如果 (3) 是这种情况，您应该停止这样做，但我认为这是最不可能的情况。如果是 (1) 或 (2)，您可以缓解问题的主要方法是确保快速获取 Statement，以便在我们等待 Statement 时不太可能发生坏事。

我首先要看的是 c3p0 的线程池在您的应用程序所承受的负载条件下。跟得上吗？（您可以通过 JMX 或通过调用 PooledDataSource 方法（如 getThreadPoolNumTasksPending()）来检查这一点，或者，最简单的做法是简单地扩展 c3p0 配置参数 numHelperThreads，因此不太可能像 Statement 获取这样的任务被积压.

另一个真正有用的配置更改是确保您允许足够数量的缓存语句以防止搅动（不断关闭（）并重新获取语句缓存中的连接）。一个非常常见的配置错误是将全局 maxStatements 配置参数设置为过低的值。获得此权利的简单方法是使用maxStatementsPerConnection，而不是全局限制，并将其设置为大约您的应用程序经常使用的 PreparedStatements 数量。

要真正了解发生了什么，您需要了解哪些任务积压了。再次直接在代码中或通过 JMX 使用 PooledDataSource.sampleThreadPoolStatus()。

更新：在原始帖子中，您声明“准备好的语句缓存大小将其保持为默认值”。这可能是 mule 的默认设置，但 c3p0 的默认设置是根本不使用语句缓存，maxStatements=0 和maxStatementsPerConnection=0。您的配置可能不是您认为的那样。禁用语句缓存可能是解决此问题的一种非常简单的方法。

【讨论】：