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POcom.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure when executing Large queries
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i am using hibernate 3.0 in my web application and using Mysql as the database. everything is working fine in normal circumstances, but the problem arises when i am trying to execute a large query mysql is terminating the connection automatically after sometime. My hibernate.cfg.xml looks like this. com.mysql.jdbc.Driver <pre><code><property name="hibernate.connection.url">jdbc:mysql://localhost:3306/MY_DB</property> <property name="hibernate.connection.username">username</property> <property name="hibernate.connection.password">password</property> <property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>  <property name="hibernate.c3p0.min_size">1</property> <property name="hibernate.c3p0.max_size">500</property> <property name="hibernate.c3p0.timeout">600</property> <property name="hibernate.c3p0.max_statements">50</property> <property name="hibernate.c3p0.idle_test_period">0</property> <property name="hibernate.max_fetch_depth">0</property> <property name="hibernate.propertyCycle">300</property> <property name="hibernate.acquireIncrement">3</property> <property name="hibernate.numHelperThreads">6</property> <property name="hibernate.unreturnedConnectionTimeout">600</property> <property name="connection.autoReconnect">true</property> <property name="hibernate.connection.release_mode">after_statement</property> <property name="hibernate.transaction.flush_before_completion">true</property> <property name="connection.autocommit">false</property> <property name="hibernate.hbm2ddl.auto">update</property> </code></pre> and my my.cnf looks like this <pre><code>[mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 max_allowed_packet = 2G max_connections = 50000 max_connect_errors = 1000 connect_timeout = 20 default-storage-engine=innodb innodb_file_per_table innodb_flush_method=O_DIRECT innodb_log_file_size=500M innodb_buffer_pool_size=2G innodb_additional_mem_pool_size = 200M open-files-limit=50000 wait_timeout=600 connect_timeout=600 interactive_timeout=600 [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid </code></pre> and the stacktrace when i am executing large queries is as follows : <pre><code>org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: could not execute query at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:656) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:119) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:177) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:169) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298) 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:99) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.loader.Loader.doList(Loader.java:2536) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276) at org.hibernate.loader.Loader.list(Loader.java:2271) at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:316) at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1842) at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165) at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:157) at co.in.gems.student.dao.impl.StudentPlacementDetailDaoImpl.getAllStudentsforPlacementByCriteriaInstituteCourseId(StudentPlacementDetailDaoImpl.java:2298) at co.in.gems.student.service.impl.StudentPlacementDetailManagerImpl.getAllStudentsforPlacementByCriteriaInstituteCourseId(StudentPlacementDetailManagerImpl.java:587) at co.in.gems.placements.controller.StudentPlacementStatisticsController.fetchStudentStatisticswithMultipleCriterias(StudentPlacementStatisticsController.java:174) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644) ... 48 more Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet successfully received from the server was 317,689 milliseconds ago. The last packet sent successfully to the server was 317,688 milliseconds ago. at sun.reflect.GeneratedConstructorAccessor217.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:407) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3082) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2968) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3516) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1986) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2140) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2626) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2111) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2273) 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:1953) at org.hibernate.loader.Loader.doQuery(Loader.java:802) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274) at org.hibernate.loader.Loader.doList(Loader.java:2533) ... 67 more Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost. at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2529) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2979) ... 80 more </code></pre> i don't know where i am missing something...
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com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure when executing Large queries
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