Troubleshooting & Debugging Focus for Weblogic

JDBC:

Problem Overview:

Stale database connections in WebLogic occur when connections remain open but are no longer in use by applications. This leads to:

• High CPU usage (database server struggles with managing dead connections)

  
  

  • High memory consumption (each idle connection consumes resources)

    
    

    • Database breakdown (connection pool exhaustion leading to "ORA-00020: maximum number of processes exceeded" or similar errors)

      
      

      Root Causes:

      
      
      Improper Connection Handling
      
      

      • Missing connection.close() in application code (JDBC leaks)

        
        

        Transactions left open without commit/rollback
        

        
        
      • JDBC Pool Misconfiguration
      • 
        

      • Missing TestConnectionsOnReserve or InactiveConnectionTimeout

        • Overly large MaxCapacity with no proper cleanup

          
          

          Network/DB Failures

          
          

          • Database restarts or network drops leaving connections in a zombie state

            
            

            Long-Running Queries

            
            

            • Queries that hang indefinitely (e.g., due to locks or bad SQL)

              
              

              Detection Methods:

              
              

              WebLogic Console Checks

              Navigate to:

              S

              • • • • ervices → JDBC → DataSources → YourDataSource → Monitoring

              Database-Level Checks

              Oracle

              
              

              SELECT username, status, COUNT(*) FROM v$session 

              WHERE status='INACTIVE' AND username IS NOT NULL 

              GROUP BY username, status;

              
              

              MySQL

              
              

              SHOW PROCESSLIST; -- Look for long-running "Sleep" connections

              
              

              Thread Dump Analysis

              
              

              Check for stuck threads holding DB connections:

              
              

              jstack <WebLogic_PID> | grep -A 20 "oracle.jdbc.driver"

              
              

              
              

              WLST Script Example to Update Pool Settings

              
              

              edit()

              startEdit()

              cd('/JDBCSystemResources/YOUR_DATASOURCE/JDBCResource/YOUR_DATASOURCE/JDBCConnectionPoolParams/YOUR_DATASOURCE')

              set('InactiveConnectionTimeout', 30)

              set('TestConnectionsOnReserve', 'true')

              save()

              activate()