间歇性获取Google应用程序引擎上的异常“ org.hibernate.exception.JDBCConnectionException：无法打开连接”

Question

我在我的项目中使用Google App引擎，CloudSQL和Hibernate。 最近几天，我收到一段时间的异常“ org.hibernate.exception.JDBCConnectionException：无法打开连接”，一段时间后它消失了。 错误日志显示错误发生在大约50％的API调用中

检查了休眠配置，似乎是正确的
现在这已成为一个主要问题。 任何帮助表示赞赏。

<property name="hibernate.bytecode.use_reflection_optimizer">false</property>     
<property name="hibernate.connection.driver_class">com.mysql.jdbc.GoogleDriver</property>
<property name="hibernate.connection.url">jdbc:google:mysql://<my cloud SLQ instance>/<mydb></property>
<property name="hibernate.connection.username">xxxx</property>
<property name="hibernate.connection.password">xxxx</property>
<!-- JDBC connection pool (use the built-in) -->
<property name='connection.pool_size'>1</property> 
<!-- SQL dialect -->
<property name='hibernate.dialect'>org.hibernate.dialect.MySQLDialect</property>
<!-- Echo all executed SQL to stdout -->
<property name='show_sql'>false</property>  
<!-- Drop and re create schema -->
<property name='hbm2ddl.auto'>update</property> 

这是异常日志

  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
W 13:31:43.908 /productList
  org.hibernate.exception.JDBCConnectionException: Could not open connection
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:131)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:221)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:56)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:161)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:182)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1854)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1831)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1811)
    at org.hibernate.loader.Loader.doQuery(Loader.java:899)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:311)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2111)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:82)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:72)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3917)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:460)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:429)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:206)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:262)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:150)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1091)
    at org.hibernate.internal.SessionImpl.access$2000(SessionImpl.java:174)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2473)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:987)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:38)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:30)
    at com.shimplify.servlet.ProductList.doGet(ProductList.java:77)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:257)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:482)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:230)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:234)
    at java.lang.Thread.run(Thread.java:745)
  Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:350)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2416)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2450)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2235)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:818)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.GeneratedConstructorAccessor34.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:404)
    at com.mysql.jdbc.GoogleNonRegisteringDriver$JdbcWrapper.getInstance(GoogleNonRegisteringDriver.java:276)
    at com.mysql.jdbc.GoogleNonRegisteringDriver.connect(GoogleNonRegisteringDriver.java:246)
    at org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:204)
    at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:292)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157)
  <continued in next message>
W 13:31:43.908 <continued from previous message>
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:56)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:161)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:182)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1854)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1831)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1811)
    at org.hibernate.loader.Loader.doQuery(Loader.java:899)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:311)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2111)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:82)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:72)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3917)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:460)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:429)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:206)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:262)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:150)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1091)
    at org.hibernate.internal.SessionImpl.access$2000(SessionImpl.java:174)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2473)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:987)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:38)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:30)
    at com.shimplify.servlet.ProductList.doGet(ProductList.java:77)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:230)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    ... 1 more
  Caused by: java.net.SocketException: Unable to open connection to the instance: boxnsights:boxnsightsdb
    at com.mysql.jdbc.GoogleCloudSqlSocket.<init>(GoogleCloudSqlSocket.java:48)
    at com.mysql.jdbc.GoogleCloudSqlSocketFactory.connect(GoogleCloudSqlSocketFactory.java:81)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
    ... 67 more
  Caused by: java.io.FileNotFoundException: /cloudsql/boxnsights:boxnsightsdb (No such file or directory)
    at java.io.RandomAccessFile.open(Native Method)
    at java.io.RandomAccessFile.<init>(RandomAccessFile.java:259)
    at java.io.RandomAccessFile.<init>(RandomAccessFile.java:136)
    at com.mysql.jdbc.GoogleCloudSqlSocket$RandomAccessFileHelper.getFile(GoogleCloudSqlSocket.java:249)
    at com.mysql.jdbc.GoogleCloudSqlSocket.<init>(GoogleCloudSqlSocket.java:46)
    ... 69 more
F 13:31:43.914 Uncaught exception from servlet
  org.hibernate.exception.JDBCConnectionException: Could not open connection
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:131)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:221)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:56)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:161)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:182)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1854)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1831)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1811)
    at org.hibernate.loader.Loader.doQuery(Loader.java:899)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:311)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2111)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:82)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:72)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3917)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:460)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:429)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:206)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:262)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:150)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1091)
    at org.hibernate.internal.SessionImpl.access$2000(SessionImpl.java:174)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2473)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:987)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:38)
    at com.shimplify.core.DaoUtil.getById(DaoUtil.java:30)
    at com.shimplify.servlet.ProductList.doGet(ProductList.java:77)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:257)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:482)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:230)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:234)
    at java.lang.Thread.run(Thread.java:745)
  Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:350)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2416)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2450)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2235)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:818)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.GeneratedConstructorAccessor34.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:404)
    at com.mysql.jdbc.GoogleNonRegisteringDriver$JdbcWrapper.getInstance(GoogleNonRegisteringDriver.java:276)
    at com.mysql.jdbc.GoogleNonRegisteringDriver.connect(GoogleNonRegisteringDriver.java:246)
    at org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:204)
    at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:292)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPrep...(length 13134)

Answer 1

在我看来，您始终不会close /断开Hiberante的会话。 为了确保它总是发生，无论抛出什么异常，您都可以在try/finally块中执行代码，否则该连接不会返回到JDBC池（那里的连接数是有限的）。

如果使用JPA API，则应调用EntityManager.close()方法。

Answer 2

开始使用后，我的问题解决了

ServiceRegistryBuilder builder = new ServiceRegistryBuilder().applySettings(configuration.getProperties());
SessionFactory sessionFactory = configuration.buildSessionFactory(builder.buildServiceRegistry());

以前，我使用过时的方法（如下），该方法似乎在有限的时间内有效，然后开始为大约50％的调用提供错误。

SessionFactory sessionFactory = configuration.buildSessionFactory();

我正在使用hibernate 4.2，所以没有使用StandardServiceRegistryBuilder