С перерывом получается исключение «org.hibernate.exception.JDBCConnectionException: Не удалось открыть соединение» в Google приложении engine

Question

Я использую движок Google App, CloudSQL и Hibernate в своем проекте. За последние несколько дней я получаю исключение «org.hibernate.exception.JDBCConnectionException: Не удалось открыть соединение» в течение некоторого времени, и через некоторое время он уходит. Журнал ошибок показывает ошибка происходит из-за примерно 50% моего API вызовов

проверили конфигурацию спящего режима и, похоже, прав
Это стало серьезной проблемой в настоящее время. Любая помощь приветствуется.

<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> 

Вот журнал исключение

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

Моя проблема решена после того, как я начал использовать

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

Раньше я использовал устаревшую метод (ниже), который, казалось, работать на ограниченное время быть затем начал давать ошибки около 50% вызовов.

SessionFactory sessionFactory = configuration.buildSessionFactory(); 

Я использую спящий режим 4.2, так не использовали StandardServiceRegistryBuilder

Answer 2

Мне кажется, вы не всегда close/отключить сеанс Hiberante в. Чтобы убедиться, что это всегда происходит, независимо от того, какое исключение выбрано, вы можете выполнить свой код в блоке try/finally, иначе соединение не будет возвращено в пул JDBC (где у вас ограниченное количество подключений).

Если вы используете API JPA, вы должны вызвать метод EntityManager.close().