Hi,
I have a web application running on Tomcat4.1, using postgresql 7.5 database. Hibernate 2.1.x is being used along with jdbc driver pg74.1jdbc3.jar for mapping database.

The application dumps the following error in the following cases:
1. The postgres process is restarted.
2. The network connection between the machine running postgres and tomcat has been reset.

Hibernate data source property ( hibernate.connection.datasource) is being used for identifying the database.

Any idea how to make tomcat reconnect to the database with out any problems ?

Any help is appreciated.

Thanks
Kishore Kolli
Software Engineer
Siemens


15:38:01,666 ERROR [JDBCTransaction] Begin failed
org.postgresql.util.PSQLException: An I/O error has occured while flushing the output - Exception: java.net.SocketException: Connection reset by peer: socket write error
Stack Trace:

java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
at org.postgresql.core.PGStream.flush(PGStream.java:412)
at org.postgresql.core.QueryExecutor.sendQueryV3(QueryExecutor.java:339)
at org.postgresql.core.QueryExecutor.executeV3(QueryExecutor.java:122)
at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:101)
at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:43)
at org.postgresql.jdbc1.AbstractJdbc1Connection.execSQL(AbstractJdbc1Connection.java:867)
at org.postgresql.jdbc1.AbstractJdbc1Connection.setAutoCommit(AbstractJdbc1Connection.java:1258)
at org.apache.commons.dbcp.DelegatingConnection.setAutoCommit(DelegatingConnection.java:266)
at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.setAutoCommit(PoolingDataSource.java:338)
at net.sf.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:44)
at net.sf.hibernate.transaction.JDBCTransactionFactory.beginTransaction(JDBCTransactionFactory.java:19)
at net.sf.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:2158)
at com.siemens.sn.phoenix.db.DbSession.beginDbTransaction(DbSession.java:291)
at com.siemens.sn.phoenix.db.DbSession.beginTransaction(DbSession.java:282)
at com.siemens.sn.phoenix.bl.ObjectMgr.getDomainObjects(ObjectMgr.java:49)
at com.siemens.sn.phoenix.ui.NpmBasePage.getObjectList(NpmBasePage.java:1657)
at com.siemens.sn.phoenix.ui.NpmBasePage.getObjectList(NpmBasePage.java:1579)
at org.apache.jsp.base_jsp._jspService(base_jsp.java:253)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666)
at java.lang.Thread.run(Thread.java:595)
End of Stack Trace

at org.postgresql.core.PGStream.flush(PGStream.java:416)
at org.postgresql.core.QueryExecutor.sendQueryV3(QueryExecutor.java:339)
at org.postgresql.core.QueryExecutor.executeV3(QueryExecutor.java:122)
at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:101)
at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:43)
at org.postgresql.jdbc1.AbstractJdbc1Connection.execSQL(AbstractJdbc1Connection.java:867)
at org.postgresql.jdbc1.AbstractJdbc1Connection.setAutoCommit(AbstractJdbc1Connection.java:1258)
at org.apache.commons.dbcp.DelegatingConnection.setAutoCommit(DelegatingConnection.java:266)
at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.setAutoCommit(PoolingDataSource.java:338)
at net.sf.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:44)
at net.sf.hibernate.transaction.JDBCTransactionFactory.beginTransaction(JDBCTransactionFactory.java:19)
at net.sf.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:2158)
at com.siemens.sn.phoenix.db.DbSession.beginDbTransaction(DbSession.java:291)
at com.siemens.sn.phoenix.db.DbSession.beginTransaction(DbSession.java:282)
at com.siemens.sn.phoenix.bl.ObjectMgr.getDomainObjects(ObjectMgr.java:49)
at com.siemens.sn.phoenix.ui.NpmBasePage.getObjectList(NpmBasePage.java:1657)
at com.siemens.sn.phoenix.ui.NpmBasePage.getObjectList(NpmBasePage.java:1579)
at org.apache.jsp.base_jsp._jspService(base_jsp.java:253)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666)
at java.lang.Thread.run(Thread.java:595)

The basic idea is to use connection pool and configure it to validate connection before returning it to the requestor. This is pool specific configuration details.
http://www.mchange.com/projects/c3p0/index.html

http://www.informit.com/articles/articl ... Num=4&rl=1