strategy for jdbc connection errors

From:
Jan Helgesen <spam@nospam.com>
Newsgroups:
comp.lang.java.help
Date:
Sun, 21 Jun 2009 12:54:07 +0200
Message-ID:
<4a3e114f$1@news.broadpark.no>
Hi

Anybody got any best practices for how to deal with connection problems
in JDBC with commons DBCP/Pool?

I am working on a storage tier where the DAOs can encounter faulty
database connections, either closed or other-wise non functional
connections. The database connection is pooled with Commons DBCP/Pool
and my initial thought was to reinitialise or restart the pool, if any
problems are encountered of that sort..

I then realised that the pool can test the connections before leasing it
to the application. This moves me into muddy waters, because I dont know
much about these details and I am having trouble finding decent
documentation on the subject.

My original code is something like:

   while (retry > 0) {
     Connection con = ds.getConnection();

     if (con==null) {
         dsFactory.restartDS();
         retry--:
         continue;
     }

     try {

        dao1.execute();
        dao2.execute();
        retry=0; // Completed succesfully

     } catch (SQLExceptions e) {

         if (retry == 0) {
           throw new FaultRuntimeException("Failed operation...", e);

         retry--:
         continue;
     }
     con.close();
   }

Not knowing the details of how the DBCP, DataSource or JDBC works in
these situations, this code is prone to problems.

I will continue to investigate, but any feedback about the details of
DBCP, Pool or what to look at is appreciated.

regards

Jan

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