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In busy database environments, inactive or dead connections can accumulate, consuming resources and potentially causing performance issues. This article explores how to manage inactive Oracle sessions using Dead Connection Detection (DCD) and resource parameters like , to keep database performance optimal.
Inactive sessions typically arise from applications or systems that fail to close connections properly. These sessions might be due to users closing their devices without logging out or network disruptions. Over time, unmanaged idle connections can lead to issues, including resource exhaustion.
Oracle's Dead Connection Detection (DCD) feature helps identify inactive connections between the client and server. Set in the configuration file, specifies a time interval (in minutes) to send a probe to check if connections are still active.
Benefits: DCD is effective for connections terminated due to network or client issues, freeing server-side resources.
Limitations: It does not work for bequeathed connections and may slightly impact network performance due to additional traffic.
Oracle provides the parameter within user profiles to manage idle sessions, setting the maximum duration of inactivity allowed per session.
3. Monitor the idle session. Once the When the threshold is reached, PMON marks the session as "sniped." The session will remain visible in until it attempts a new operation, at which point Oracle cleans it up.
Example: Suppose a user is assigned to profile , which has an idle time limit of 30 minutes. If the session is inactive beyond this limit, Oracle will mark it as "sniped" and clean up when the user attempts a new action.
Note: It's best to create custom profiles for users who require resource limits instead of altering default settings.
Oracle's Resource Manager provides further control over managing inactive sessions. By configuring a Resource Manager plan, you can specify the for sessions, which will automatically kill sessions exceeding the idle threshold.
For more detailed implementation, refer to Oracle documentation or trusted resources. Resource Manager is suitable for environments where detailed control over session management is necessary.
To maintain optimal database performance, consider using profiles to combine DCD with resource limits. This dual approach targets both idle and dead connections:
Caution: While DCD and Resource Manager can manage many inactive sessions, they won't eliminate all OS-level processes. Occasionally, manual cleanup of OS processes may still be necessary to free system resources completely.
Automating the cleanup of inactive sessions in the Oracle Database is vital for maintaining resource efficiency and avoiding performance issues. By leveraging DCD, idle time settings, and Resource Manager, DBAs can ensure their databases remain responsive, even under heavy load. Regularly monitor inactive sessions and apply best practices to keep your database environment streamlined and resource-efficient.