JDBC connection unexpectedly becomes null

Question

I have a problem connecting a database with JDBC (DB2). I recently implemented transaction management (commit / rollback) in a block of code, and I use the same connection for all my queries / operations in the database. We never explicitly close the connection between each request / operation. However, at runtime we get an exception indicating that our connection is invalid (closed / null). When I debug step by step, it seems that the connection fields unexpectedly become null. This looks random and it never happens on the same line. I am sure that we ourselves do not close the connection! We use the connection pool in Tomcat.

Here is a sample code:

 try {  
 connection = DB.getConnection();
 connection.setAutoCommit(false);   
 savepoint = connection.setSavepoint("avantModif");

    /*  * Here are some queries and operations that runs without error
 when the connection is not null    */      
 connection.commit(); 

} 

catch(Exception e) {

    if (connection != null && !connection.isClosed() && savepoint != null)
      {         
           connection.rollback(savepoint);  
      }

    throw e; 
} 

finally 
{   
if(connection != null){     
    connection.close();

} 

Here is a screenshot of the debugger showing the contents of the Connection object:

Tomcat server.xml:

  <Resource  
  name="jdbc/dbcpGlobal"
   auth="Container"
   type="javax.sql.DataSource"
   driverClassName="com.ibm.as400.access.AS400JDBCDriver"
   url="jdbc:as400://lvq400/apilib;naming=system;errors=full;date format=iso;prompt=false;trace=false;reconnect=true"
   username="[here_is_our_username]" password="[here_is_our_password]"
   maxIdle="7" maxActive="15" maxWait="5"
   removeAbandoned="true" removeAbandonedTimeout="120" logAbandoned="true"
   testOnBorrow="true" testOnReturn="true" validationQuery="select 1 from sysibm/sysdummy1" />

null, !

, JDBC ?

Answer 1

, . , , -, "" . , Tomcat - , . - , , logAbandoned = "true"?