Question

I get this error randomly when the web service is accessed.It is difficult to replicate and once I refresh it everything functions as expected.

  

    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)
        at org.hibernate.loader.Loader.doList(Loader.java:2235)
        at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
        at org.hibernate.loader.Loader.list(Loader.java:2124)
        at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:118)
        at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1597)
        at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
        at edu.asd.myproj.hibernate.adapter.CriteriaAdapter.list(CriteriaAdapter.java:380)
        at edu.asd.myproj.DaoHibernateImpl.findByCriteria(DaoHibernateImpl.java:778)
        at edu.asd.myproj.DaoHibernateImpl.findByCriteria(DaoHibernateImpl.java:765)
        at edu.asd.myproj.DaoHibernateImpl.findByProperty(DaoHibernateImpl.java:361)
        at edu.asd.myproj.ProfilesDaoImpl.count(ProfilesDaoImpl.java:81)
        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.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy27.count(Unknown Source)
        at edu.asd.myproj.ResourceProfileLoaderNew.loadProfiles(ResourceProfileLoaderNew.java:66)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:297)
        at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:250)
        at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:144)
        ... 50 more
    Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was44323 seconds ago.The last packet sent successfully to the server was 44323 seconds ago, which  is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        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.send(MysqlIO.java:3246)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1917)
        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 org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
        at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
        at org.hibernate.loader.Loader.getResultSet(Loader.java:1812)
        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:2232)
        ... 79 more
    Caused by: java.net.SocketException: Broken pipe
        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 com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3227)
        ... 90 more

This is my hibernate.properties file

# Turn on for SQL debugging
hibernate.show_sql=true

# Generate schema?
hibernate.hbm2ddl.auto=validate

#============================================================
# C3P0 connection pool configuration
#============================================================
#changed to default values 
c3p0.acquireIncrement=hibernate.c3p0.acquire_increment
c3p0.idleConnectionTestPeriod=hibernate.c3p0.idle_test_period
c3p0.initialPoolSize=10
c3p0.maxIdleTime=hibernate.c3p0.timeout
c3p0.maxPoolSize=hibernate.c3p0.max_size
c3p0.maxStatements=hibernate.c3p0.max_statements
c3p0.minPoolSize=hibernate.c3p0.min_size   
c3p0.testConnectionsOnCheckout=hibernate.c3p0.validate

The error is seen randomly once and it takes a long time before it reappears.It goes away once refreshed.

Answer 1

Please send complete exception stack trace for more understanding of reader.

This exception occured usually when a DB Connection stale.

Stale means: connection killed by the server, but still considered alive by the pool. You need to configure connection testing in the connection. For this approach in C3P0 you have to using following configuration:

c3p0.testConnectionOnCheckin = true
testConnectionOnCheckout= true

and for more checking increase checkout timeout as following:

c3p0.checkoutTimeout = 0

and test another test options in C3P0 such as :

• connectionTesterClassName
• idleConnectionTestPeriod
• automaticTestTable
• preferredTestQuery

Another way for test is writing a sample code and connect to database by a JDBC pure codes.(by DriverManager and Connection and etc )