私はこれが何度も尋ねられたことを知っていますが、私はそれに固執しています。
私は次のことを確認しました：
IP address or hostname in JDBC URL is correct.
Hostname in JDBC URL is also recognized by local DNS server.
Port number is correct in JDBC URL.
DB server is up.
同じDB呼び出しが機能することもあるので、「接続外」に関連していると思います。50-60 connections発行時にはDBのみでした。
C3PO connectionsそれでも、それは使い果たされたかもしれないと私は信じています。
以下のC3P0構成があります
<props>
<prop key="hibernate.c3p0.timeout">
44000
<!-- seconds -->
</prop>
<prop key="hibernate.c3p0.min_size">5</prop>
<prop key="hibernate.c3p0.max_size">5</prop>
<prop key="hibernate.c3p0.initial_pool_size">5</prop>
<prop key="hibernate.c3p0.idle_test_period">
60
<!-- seconds -->
</prop>
<prop key="hibernate.c3p0.acquire_increment">2</prop>
<prop key="hibernate.c3p0.max_statements">50</prop>
<prop key="hibernate.c3p0.preferredTestQuery">SELECT 1 FROM DUAL</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
ほとんどのエントリはここでは定義されておらず、デフォルトが使用されます。これが問題である可能性があり、理由が非常に役立つかどうかを教えてください。
Maximum number C3P0 connections by default are 15ただし、ほぼ常にこの制限を超えており、この問題に直面することはありません（acquireIncrementこのシナリオでも、接続をサポートするのはC3P0のプロパティのbcozである可能性があります）。
スタックトレース：
org.springframework.dao.DataAccessResourceFailureException: could not execute query; nested exception is org.hibernate.exception.JDBCConnectionException: could not execute query
at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:625)
at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.convertHibernateAccessException(AbstractSessionFactoryBean.java:303)
at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.translateExceptionIfPossible(AbstractSessionFactoryBean.java:282)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:58)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:163)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at $Proxy34.findByName(Unknown Source)
at a.b.c.d.e.f(A.java:941)
at a.b.c.d.e.f$$FastClassByCGLIB$$a171eb15.invoke(<generated>)
at org.springframework.internal.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621)
at com.amazon.mobiusdatabase.activity.IMBatchActivity$$EnhancerByCGLIB$$42d90986.getLatestBatchByStatus(<generated>)
at com.amazon.coral.reflect.$2198.invoke(Unknown Source)
at com.amazon.coral.service.DefaultActivityInvoker.invoke(DefaultActivityInvoker.java:40)
at com.amazon.coral.service.ContinuationActivityInvokerFactory$1.invoke(ContinuationActivityInvokerFactory.java:92)
at com.amazon.coral.service.ActivityHandler.invoke(ActivityHandler.java:269)
at com.amazon.coral.service.ActivityHandler.before(ActivityHandler.java:157)
at com.amazon.coral.service.TransmutingContinuationHandler.before(TransmutingContinuationHandler.java:51)
at com.amazon.coral.service.Chain.componenteBefore(Chain.java:98)
at com.amazon.coral.service.Chain.before(Chain.java:76)
at com.amazon.coral.service.helper.ChainHelper.before(ChainHelper.java:103)
at com.amazon.coral.service.AbstractOrchestrator.doWork(AbstractOrchestrator.java:60)
at com.amazon.coral.service.PassiveOrchestrator.enqueue(PassiveOrchestrator.java:68)
at com.amazon.coral.service.GracefulShutdownOrchestrator.enqueue(GracefulShutdownOrchestrator.java:79)
at com.amazon.coral.service.helper.OrchestratorHelper.enqueue(OrchestratorHelper.java:44)
at com.amazon.coral.service.batch.BatchProtocolOrchestrator.enqueue(BatchProtocolOrchestrator.java:97)
at com.amazon.coral.service.bobcat.BobcatEndpoint.invoke(BobcatEndpoint.java:194)
at org.apache.catalina.valves.SSLValve.invoke(SSLValve.java:113)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:894)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:719)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:2101)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:97)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 1 ms ago.
at sun.reflect.GeneratedConstructorAccessor143.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2985)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1885)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1808)
at org.hibernate.loader.Loader.doQuery(Loader.java:697)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2228)
... 49 more
Caused by: java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:168)
at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:113)
at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:160)
at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:188)
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2428)
DBでselectクエリを実行しているときにこれを取得しています。