Tomcat DBCP Running out of connections

Question

I'm encountering a ORA-12519, TNS:no appropriate service handler found error when attempting to integrate Tomcat's JDBC Pool into my web application, using Oracle.

I typically see this error appear intermittently, after several minutes of running integration tests against the application.

The configuration I have is:

• oracle driver and tomcat-dbcp jars in the tomcat/lib directory

• two webapps, both using the same Resources. Configuration done in Spring:

  <jee:jndi-lookup id="webDS" jndi-name="jdbc/web"
      expected-type="javax.sql.DataSource" />
  

• DataSource Resources defined in conf/context.xml, as follows:

  <Resource name="jdbc/web" auth="Container" 
  type="javax.sql.DataSource" 
  factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" 
  testWhileIdle="true" 
  testOnBorrow="true" 
  testOnReturn="false" 
  validationQuery="SELECT 1" 
  timeBetweenEvictionRunsMillis="30000" 
  maxActive="20" 
  maxIdle="10" 
  minIdle="5" 
  removeAbandonedTimeout="60" 
  removeAbandoned="false" 
  logAbandoned="true" 
  minEvictableIdleTimeMillis="30000" 
  jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer" 
  username="${database.user}" 
  password="${database.password}" 
  driverClassName="${database.driver}" 
  url="${database.url}" />
  

I've tried various suggestions made elsewhere on SO such as increasing or decreasing the maxActive size, but am having no luck thus far. I was previously using c3p0 to manage the pool of connections. With the switch, I'm wondering if there is some additional configuration I need to do that pertains to the closing of connections, because it seems like I'm leaking them.

The stack trace:

Caused by: org.hibernate.exception.GenericJDBCException: Could not open connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:124)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:109)
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$5.doPrepare(StatementPreparerImpl.java:159)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:183)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:157)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1881)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1858)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1838)
at org.hibernate.loader.Loader.doQuery(Loader.java:906)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:348)
at org.hibernate.loader.Loader.doList(Loader.java:2550)
at org.hibernate.loader.Loader.doList(Loader.java:2536)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2366)
at org.hibernate.loader.Loader.list(Loader.java:2361)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:495)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:357)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:198)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1230)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:268)
... 112 more
Caused by: java.sql.SQLException: Listener refused the connection with the following error:
ORA-12519, TNS:no appropriate service handler found

at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:489)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:553)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:254)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:528)
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:278)
at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:182)
at org.apache.tomcat.jdbc.pool.PooledConnection.reconnect(PooledConnection.java:315)
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:803)
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:628)
at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:187)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:128)
at org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider.getConnection(InjectedDataSourceConnectionProvider.java:70)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:301)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)
... 132 more
Caused by: oracle.net.ns.NetException: Listener refused the connection with the following error:
ORA-12519, TNS:no appropriate service handler found

at oracle.net.ns.NSProtocol.connect(NSProtocol.java:399)
at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1140)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:340)
... 146 more

Answer 1

Your validation query (SELECT 1) will not work in Oracle. It has to be select 1 from dual.

Seems that when using a wrong validation query the application is not able to identify healthy connections and and mark all of them as invalid.